Yes, People Dislike MUI. Here Are 6 Key Reasons Why

Introduction: The Love-Hate Relationship with MUI

MUI (formerly Material-UI) is a titan in the React ecosystem. It’s a comprehensive library of UI components that empowers developers to build feature-rich, accessible, and consistent-looking applications with remarkable speed. For many, it’s the go-to choice for admin dashboards, internal tools, and complex web apps. So why, despite its immense popularity, does it generate so much debate and, in some circles, outright dislike?

The truth is, no tool is perfect for every job. The very strengths that make MUI a powerhouse in some scenarios become its greatest weaknesses in others. This isn't a post to bash a valuable open-source project, but rather to explore the valid criticisms and trade-offs. Understanding these pain points is crucial for any developer or team deciding whether MUI is the right fit for their next project. Let's dive into the six key reasons why some people dislike MUI.

1. The Overriding Styles Conundrum

Perhaps the most common frustration with MUI revolves around customization. While MUI is highly themeable, making specific, one-off style changes can feel like you're fighting the library. MUI v5 uses Emotion as its default styling engine, which offers two primary ways to apply custom styles:

• The sx prop: This is a convenient superset of CSS that allows you to write style rules directly on a component. It's great for quick tweaks but can lead to bloated JSX and mix styling concerns directly into your component logic.
• The styled() utility: This is the more robust, recommended approach for creating reusable, styled versions of components. However, it’s more verbose and requires a separate component definition.

The real pain begins when you need to override the style of a deeply nested element within a complex component, like changing the color of the checkmark inside a Checkbox or the border of a TextField only when it's focused. This often forces you to use browser dev tools to hunt down MUI's internal class names (e.g., .Mui-focused, .MuiInputBase-root) and write complex, sometimes brittle, global style overrides. For developers accustomed to the simplicity of Tailwind CSS or CSS Modules, this feels cumbersome and unintuitive.

2. The Bundle Size Dilemma

MUI is a heavyweight. It's a "batteries-included" library, which means it comes with a vast array of components, a complete styling engine, and numerous utilities. While the MUI team has done excellent work to ensure it's tree-shakable (meaning your final bundle should only include the code you actually use), the baseline cost is still significant.

Even importing a single Button can pull in a non-trivial amount of code from the core and styling packages. For a large-scale internal application or an admin dashboard behind a login, a few extra kilobytes is a worthy trade-off for development speed. But for a public-facing marketing site or a performance-critical e-commerce application, every kilobyte counts. The initial bundle size can negatively impact key performance metrics like First Contentful Paint (FCP) and Time to Interactive (TTI), which affects both user experience and SEO rankings. In these cases, lighter alternatives often win out.

3. API Complexity and a Steep Learning Curve

With great power comes a great number of props. MUI's components are incredibly powerful, but this power is exposed through a vast and sometimes intimidating API. A component like Autocomplete or DataGrid can have hundreds of props, each controlling a different facet of its appearance and behavior.

Component Composition Adds Another Layer

Furthermore, many MUI components are not monolithic but are composed of several smaller components. A simple TextField, for instance, is actually a composition of FormControl, InputLabel, and OutlinedInput (or FilledInput/Input). While this compositional model provides immense flexibility, it adds a significant cognitive load for newcomers who must learn not just one component, but an entire system of related parts to achieve their desired result. This steep learning curve can slow down development initially, as developers spend considerable time poring over the extensive documentation to find the right prop or component combination.

4. The 'Generic' Material Design Look

This is a subjective but very real point of contention. By default, an application built with MUI looks... well, like a Google application. This is intentional. Material Design is a well-researched, robust design system that provides a clean, professional, and familiar user experience out of the box.

However, for projects that require a unique, highly-branded visual identity, this strong default aesthetic can be a major hurdle. To break free from the Material look, you need to do more than just change a few colors. It requires a deep dive into the themeing system to override typography, shadows, border-radii, spacing, component transitions, and more. The effort required to de-Google-ify an MUI app can sometimes be greater than building a custom design system from scratch with more flexible tools, leading many design-forward teams to opt for other solutions.

5. Runtime Performance Overhead

This is a more technical criticism related to MUI's default styling engine, Emotion. As a runtime CSS-in-JS library, Emotion calculates and injects styles into the document's <head> *as components render in the browser*. This process, while seamless for the developer, has a measurable performance cost.

Every time a component mounts or its styles change, JavaScript has to do work to compute the CSS and inject it into the DOM. While this overhead is small on a per-component basis, it can add up in complex applications, contributing to slightly longer render times and potentially a less snappy user experience. This is in contrast to zero-runtime solutions like Tailwind CSS or build-time solutions like Linaria, where all CSS is extracted into static .css files during the build process, eliminating this specific type of runtime overhead.

6. An Opinionated and Sometimes Rigid Structure

MUI is opinionated. It makes decisions for you about accessibility, state management within complex components, and DOM structure. For 80% of use cases, these opinions are a blessing, providing best practices and saving you from reinventing the wheel.

The problem arises in the other 20% of cases. When you need to deviate from the prescribed path—for example, to integrate a complex component with a different state management library or to fundamentally alter the rendered HTML for a specific design—you can find yourself in a battle against the library's abstractions. What should be a simple task can become a complex workaround, involving prop-drilling, component wrappers, or even reaching for !important in your CSS. This rigidity, born from its "batteries-included" philosophy, can be a major source of frustration for developers who need maximum control and flexibility.

MUI vs. Alternatives: A Quick Comparison

Conclusion: Is MUI Still Worth Using?

Absolutely. The criticisms leveled against MUI are valid, but they are primarily a function of context. Dislike for the library often stems from a fundamental mismatch between the project's requirements and the library's core strengths.

MUI shines brightest when its opinionated nature is an asset. It is an unparalleled tool for building complex, data-heavy admin dashboards and internal applications where development speed, consistency, and a rich feature set are more important than a unique brand identity or minimal bundle size. It provides a solid, accessible, and professional foundation right out of the box.

However, if you're building a highly-branded marketing website, a bleeding-edge performant web app, or a project where design flexibility is the top priority, MUI might feel more like a cage than a launchpad. In those cases, a utility-first library like Tailwind CSS or a set of headless components like Radix UI or React Aria might be a far better choice.

Ultimately, MUI is a powerful tool with a specific set of trade-offs. By understanding its weaknesses alongside its strengths, you can make an informed decision and choose the right tool for the right job, avoiding the frustration that comes from trying to fit a square peg in a round hole.