GearScore has it's uses. And it's really easy to get gear these days, even easier with JPs almost because as soon as you start heroics you can get T10 (no more Frost farming, though I hear there will be a higher tier form of JP during the Cata release, perhaps permanent). And honestly, WoW is sink or swim. If you have a high gear score and you suck terribly you'll be kicked from the group.
We took a disc priest in mostly T9 to LK and you know what? He talked the talk but couldn't walk the walk so we booted his ass. Honest to god I've never seen the plague get THAT bad.
We were doing HM Marrow and this hunter wasn't stacking nearly as close as he should have been, so bone spikes were a *****, but we kept him for the time being... and then we went to do ToGC 10 and he got hit by Icehowl so we kicked him.
And if you do take a hiatus, you should also expect to gear up for the newer raids :v And if there's no GearScore, people will just start using Average Item Level, since it's really the same thing or some variation. Or just armory them.
And to do ICC you should have mostly 245s, because that was the highest item level before ICC was released. And like I said, if you have no skill the raid leader should have the balls to kick you and eventually you'll have no choice but the get skill.
I also heard there are servers where GearScore literally doesn't exist.