For the original question: take a look at functional reactive programming (FRP). It takes a slightly different approach to the whole GUI problem, but, I've found, obviates some of your issues.
If you're wondering about Haskell and UIs, I think FRP is the best place to look—it provides the most pleasant semantics for programming UIs that I've come across, although most of the libraries are still a bit experimental. (Implementing the exact semantics we'd like turned out to be very difficult!)
> The reactive solutions complicates the problem rather than to simplify it. That means that they are not the correct paradigm.
That's a very hasty, superficial way to dismiss a whole paradigm!
FRP libraries have proven *difficult to implement*, but this does not mean they somehow "complicate the problem". The real insight with FRP is developing a nice semantics *for the end user* and making it simpler to work with the libraries, at the expense of a more complex implementation. It's a parallel to functional programming at large: we're willing to trade complexity in GHC in return for a nicer high-level programming environment.
Formlets are an interesting concept, but they seem to be significantly more narrow than FRP. How do formlets address continuous things like animations or mouse movement?
Also, a lot of the examples (at least on the Haskell wiki[1]) seem pretty amenable to FRP. How is
chooseBool :: Form Bool
chooseBool = enumRadio [(True, "Yes"), (False, "No")] True
significantly different from just providing a Behavior Bool in the spirit of FRP?