Malte,
I applaude that decission. Ad_form started out as a convenience hack on top of form builder. My impression is that is being overloaded with too many bells and whistles. Last time I tried ad_form I immediately ran into usability issues.
So kudos for fixing the form builder. The strength of OpenACS is in the modular architecture and not in all encompassing APIs like ad_form.
My 2 cents.
/Bart