I've seen--and done--that sort of thing in Supers play, though point-buy Supers TRPGs are their own various fishkettles. I have a druid character in in a campaign I'm running who's doing much more in the way of control/set-up stuff than direct damage; he's not being any kind of purist about it, but he's not the (or even a) primary damage dealer.
I was not saying break them and send them running. I am saying to mix things up. In my experience, If players know that they can't always rely on hyper-focusing their optimization on one thing and then rely on the other party members to always cover everything else, they are less likely to do so. This doesn't mean that there won't be any optimization (as I started in a prior post, optimization is not binary, but is on a continuum)- it just means it is less likely to be as extreme (in my experience). Of course, I also recommend giving characters a heads up prior to character generation.
Plus, I find that, on occasion, taking individual characters out of their element and requiring them to face issues outside their main focus makes things more interesting. I just focused my post on optimization, because it is the topic of the thread.
