I thought the same before, but I realized JSX/TSX makes it much easier to build and refactor apps (especially when working with medium/large teams) since you can use usual JS constructs to build your dom elements and you don't have to learn a frameworks template semantics (loops, conditions, etc.).
You also benefit from all the available js tooling (editor support for refactoring, linting, syntax highlighting, type checking, etc.).
Lastly JSX eliminates the burden of switching between the framework's template syntax and regular JS/TS when refactoring code and moving logic around.
