I'm using rails 3. OP is full of crap. Rails is a full stack framework complete with ponies, unicorns, and rainbows. Asking it to be minimal is a joke, but you can get rails pretty slimmed down if you work at it. You wouldn't want to build a full app on ActionController::Metal but you can.

The redesign has made the internal code of rails much simplier and ActiveModel is simply brilliant. I'm using CouchRestModel and having ActiveModel means I can use plugins like Formtastic right out of the box.

Rails 3 decoupled the major components. It's more modular now. I can disable ActiveRecord without the plugins I'm using getting upset that it's missing. If anything, this makes the framework less complex because you don't have to worry about interplay between the components.