7 Frustrating Reasons Why Devs Secretly Dislike MUI

1. The Customization Cliff: Easy to Start, Brutal to Master

MUI's initial appeal is its brilliant "plug-and-play" nature. Need a button? <Button>. A complex date picker? Import it, and you're done. The initial velocity is exhilarating. But the moment your designer hands you a mockup that deviates even slightly from the Material Design gospel, you hit a wall. This is what many call the "customization cliff."

Simple CSS changes become a battle against specificity. You start with the recommended sx prop, which feels convenient at first. Then, for a more complex override, you're forced to target a component's internal slot. Before you know it, you're wrestling with the styled() utility or, worse, resorting to global CSS overrides with !important just to change a border-radius on a nested element. What should be a five-minute CSS fix turns into a 30-minute spelunking expedition into MUI's component DOM structure, leaving you frustrated and questioning your life choices.

2. The Bundle Size Beast: Performance Hits You Can't Ignore

Convenience has a cost, and in MUI's case, that cost is measured in kilobytes. MUI is a heavyweight champion. It's a comprehensive library, and that comprehensiveness translates directly to bundle size. Even with modern bundlers and tree-shaking, a basic set of MUI components can add a significant amount of JavaScript and CSS to your application's initial load.

This directly impacts core web vitals, particularly First Contentful Paint (FCP) and Time to Interactive (TTI). For a small internal dashboard, this might be an acceptable trade-off. But for a performance-critical, public-facing e-commerce site or marketing page, every kilobyte counts. Developers often find themselves spending hours implementing code-splitting strategies and performance optimizations just to mitigate the impact of a library that was supposed to save them time.

3. Styling API Soup: `sx`, `styled()`, and Decision Fatigue

With the release of MUI v5, the team fully embraced Emotion as the default styling engine and introduced the sx prop as the recommended way for one-off customizations. This was meant to streamline things, but for many, it created a confusing array of choices.

A Plethora of Styling Choices

On any given day, a developer might face these options to style a component:

• The sx prop for quick, responsive, theme-aware overrides.
• The styled() utility for creating entirely new, reusable styled components.
• Global theme overrides for making sitewide changes to a component's default style.
• Plain old CSS with global class name overrides (e.g., .MuiButton-root) as a last resort.

This creates cognitive overhead and leads to inconsistent codebases. One developer might prefer the brevity of sx, while another champions the reusability of styled(). This lack of a single, opinionated styling path is a major source of friction and can make maintaining a large application a real challenge.

4. The "Everything Looks Like Google" Syndrome

MUI is a fantastic implementation of Google's Material Design. This is a robust, accessible, and well-thought-out design system. The downside? Without significant theming effort, your application will have an unmistakable "Google" aesthetic. Your app might look clean and professional, but it will also look like countless other apps built with MUI.

This is a significant problem for brands striving for a unique visual identity. While MUI's theming system is powerful, creating a truly distinct look and feel requires a deep dive into theme objects, component slot overrides, and a substantial time investment. This effort can negate some of the library's initial speed advantage, bringing you right back to the customization cliff.

5. The Pain of Major Version Upgrades

Ask any developer who lived through the migration of a large codebase from MUI v4 to v5. The collective groan is almost audible. The transition was notoriously painful. The core change from JSS (CSS-in-JS) to Emotion as the default styling engine introduced a tsunami of breaking changes, requiring massive, painstaking refactoring efforts across entire applications.

While breaking changes are sometimes necessary for the long-term health and evolution of a library, the sheer scale of the v4-to-v5 migration left a sour taste. This history creates a sense of anxiety about future upgrades, making some teams hesitant to commit to MUI for projects with a long intended lifespan, fearing another disruptive migration is always just around the corner.

6. Documentation Labyrinth: A Needle in a Haystack

Let's be fair: MUI's documentation is incredibly comprehensive. It covers almost everything you could ever want to do. But its sheer size is also its Achilles' heel. Finding the specific piece of information you need can feel like an archaeological dig.

You might be looking for a simple prop to disable the ripple effect on a button. To find it, you may have to sift through pages of advanced theming examples, detailed API tables, and CSS customization guides. The component API pages often list dozens upon dozens of props, and their descriptions can be terse. This often leads frustrated developers to external resources like Stack Overflow or GitHub Issues, which is a tell-tale sign of a documentation experience that, while complete, is not always user-friendly.

7. Leaky (and Overly Thick) Abstractions

A great component library provides the right level of abstraction, hiding complexity while remaining flexible. MUI sometimes misses this delicate balance, erring in both directions.

• Too Thick: At times, the abstraction is so thick that simple HTML tasks become complicated. Want to add a data-testid attribute for your testing library? You might have to hunt to discover if it's inputProps, InputProps, or slotProps.root that will pass your attribute to the correct underlying DOM element.
• Too Leaky: Conversely, to perform advanced customizations, the abstraction becomes "leaky." You're forced to know exactly how MUI constructs its components internally—which divs are nested where, and what internal, undocumented class names are being used. This tight coupling makes your custom styles brittle and prone to breaking with any minor library update.

MUI vs. Alternatives: A Quick Comparison

These frustrations have led many developers to explore other options. Here's how MUI stacks up against popular alternatives on key pain points.

Conclusion: It's Complicated

"Dislike" is a strong word, and perhaps it's not entirely fair. MUI is an incredibly powerful and feature-rich library that has enabled thousands of teams to build and ship complex applications with impressive speed. However, it is not a silver bullet. The frustrations developers experience are real and stem from the inherent trade-offs MUI makes: comprehensiveness over lean performance, and convention over unbridled customizability.

Recognizing these pain points doesn't mean you should abandon MUI. Instead, it means you should approach it with your eyes open, understanding the challenges you might face down the road. For the right project—especially internal tools or apps where Material Design is a perfect fit—it remains an outstanding choice. But for your next project, it's worth asking if the initial velocity is worth the potential friction later on.