Fair enough. But if the low-hanging fruit is all gone... that's when one has to get clever. And maybe, just maybe, there's a table/index that'd benefit a lot from being in a different blocksize. As I said, perhaps it's just too time-consumimg to fiddle about hunting for such candidates.
In my experience, I've yet to come across a perfectly tuned database that is performing poorly and someone says "hey, how about using a larger block size for just those things" and after moving just those things to a larger (or smaller) block size, suddenly performance improves and the day has been saved.
I really don't think I'm ever likely to either ...