Well. Overall douchiness is something you have to deal with on xbox live a fair amount. But, I think clan tags are nice to add a little creative touch to your permanent gamertag (unless you want to drop 10 bucks to change it). I have a bunch of friends that i play call of duty with on xbox live. If we choose to put up a clan tag, then it is usually a joke, or to make people who take things too seriously angry. Me and a good friend of mine sported opposite ends of "MCAN" and "OBMA" tags around November. He supported McCain and i supported Obama, so he put on obma and i put on mcan. When we have 6 people, when we want a map skipped, it almost always gets skipped. So we all put on the "XBLP" tag, standing for xbox live parliment. Just a little joke we find fun. When we want to play seriously and try to win, we put our daily record up. We usually get up to 9-0 or something then we lose interest (aka lose). But back on topic, i believe that if people want to support that new halo game coming out through their clan tag then they can feel free. I mean, it will most likely suck so they will look like idiots when they buy it first day it comes out and will not admit its faults.
IN CONCLUSION: Clan tags are fun and LET'S GO BILLS!!