The word "affordance" was mentioned in this thread a lot and for a reason: it is not a thing of fashion, it is essential for good UI design. If you want to engage user in interaction you must make it pretty clear what can be interacted with.
Yes: the problem with all the minimalist approaches to anything (starting with architecture) is that "we, the people" are confronted with something with which we do not know what to do.
Is this a conference hall, a chapel or a dining room?
Is this the main room, the entrance or just the aisle to the toilets?
Design, whatever designers may say, is just a means to convey a message: either it succeeds or it is bad design.
It cannot be like modern poetry or modern 'art', where either you know the code or you understand nothing. If this happens, it is not good design, it is a different thing (which may be valuable in itself but not 'design' in this context).
You can write a newspaper with telegrams. It certainly would be cheaper. It would also be unreadable.
Edit: sorry cannot help mentioning it. Minimalists are usually as 'dogmatic' as any baroque artist might be. But at least, when you see baroque art you appreciate the harmony instantly. Not so with minimalism.
