And how are you going to write all the functions for the countless different combinations of types? This is what many users of the mtl library do and it's clear that it doesn't scale, it's error prone and the code is often not even much more readable. Clearly, some kind of mechanism that is easily composable without ceremony is needed. The real problem is that lifting/unlifting monad transformers which are not monad morphisms (mostly those that have some kind of state) is inherently unsafe. This is where MonadTransControl and MonadBaseControl classes come into play and the whole controversy surrounding them. Haskellers have debated for years about the correct semantics to use here.
I don't need to write all those functions that I'll never call. I write the few that I use in my own code, which is probably doing something fun or practical rather than abstract.
(But if you use these abstractions extensively, maybe Haskell is for you?)
