That sounds like architects have been tempered by regulations moreso than having changed ambitions though, am I missing something? My understanding is that the modernist and postmodernist icons were not academics but practicing architects, sometimes both.
Similar ambitions are still there from my anecdotal experience (especially among people in the polar ends of the profession's spectrum ie. the new grads and the veterans) but most architects I meet these days while appriciative of the works of people like Corb and other modernists, completely understand their shortcomings.
But what has really curbed the possibility of anything like those movements to happen again is the neoliberal economics in contrast to the post war socialist policies of the time.
That makes sense, by post war socialism are you thinking the Warsaw pact countries or the more social-democratic elements of Keynesianism? Either way, makes sense given most development is done privately for profit now. Thanks for sharing your perspective!