A bad API, like a bad novel, feels like a trick: key information is withheld and simple relationships are hard to deduce.
I had one of those "a-ha" moments reading this. ("A-ha," I thought. "I feel a rant coming on.") This is exactly why, after building probably one of the largest web applications done with OpenACS 3.2, I never managed to like the 4.x (and now 5.x) series of that toolkit.
OpenACS 4.x and later suffer from Second-system syndrome. The effect is rather Zope-like: instead of a learning curve, you have a vertical cliff to scale before you can accomplish anything interesting.
Add in bizarre and arbitrary api changes, it's no wonder nobody except the core team really got on board with the later OpenACS versions. (I suspect that the "everything must be a named parameter" had its genesis in the proliferation of functions taking over a dozen parameters. Deprecating all functions that don't require named parameters is both taking things too far, and fixing entirely the wrong problem!)
Which is a shame. OpenACS solves a much larger problem than most web toolkits attempt, giving you registration support, permissioning, etc. out-of-the-box. The 3.x series may have solved only 90% of the problem, but it did so in a much more approachable way than 4.x. (Or Zope, the only other framework that really tried to tackle this problem in that era. Don't even get me started on J2EE systems.)
Ah, well. RIP, OpenACS. It looks like Django is trying to solve some of these same problems (e.g., its permissioning support and "pluggable applications") while retaining a more lightweight approach. In this respect, Django is much more than a me-too "Rails for Python." Of the would-be Python Rails killers (and Rails itself), Django alone impresses me for attempting more than the same old, same old.
(Which reminds me -- I haven't seen this fellow's django-and-rails comparison linked anywhere, even though it's a month old. Guess I don't follow the right blogs. It's worth reading if you don't know much about one or the other, despite his lamentable lack of taste in prefering Ruby.)