Swapping surface mount components isn't nearly as hard as people seem to think it is. The challenge is usually just buying the darned things in small quantity. However, that's becoming quite a problem on the "digital" CRT sets, too. If the micro dies, you can't get one with the right firmware on it.
Really, the reason these aren't repairable is because it isn't worth it to do so. Making the device easier to repair would inflate the price by ~10-25%, and prices are already so low that it isn't worth paying a repairman for his/her time, so why not shave the extra 10-25% off and just make replacement cost less. Besides, when it dies, you'll be able to buy something 10 times better for 1/10th the price.
As for killing an LCD by playing games on it, you won't. One of the nice things about LCDs is that pretty much nothing kills them except time.
Of course, this doesn't mean LCDs are good for gaming. I like my (very high end) LCD PC monitor just fine, but for gaming I use a Sony GDM-FW900 or a real arcade monitor (CRT, of course). I do have one cabinet with a Plasma on it (and yes, it's very burned), but that's just because you can't buy 40" widescreen CRTs.