i think the spawn camping is justified just because of the low respawn time, it allows the rest of the team to get to b/k for the cap. unfortunately the majority of players do not take advantage of this and instead join in on the camping allowing the other team to eventually clear the area and retake back to a or c/l... which is why the game rarely ends with a win, too long have i sat at 1 min left in the game for 30 mins.... if they do allow multiple exits for the spawn i think you would have to increase spawn time, which is an unfavorable choice in my opinion cause i hate waiting to play
if anything they need to make sniper battlements that spies/scouts/pyro's/demo's/everything can't get to, so i dont ever have to keep jumping off the ledge and suiciding myself.... =)