I agree, the level of awesome Masters can achieve seem to be much higher than a normal servant. The other issue is is that being a master requires much more information on the setting than a normal person is probably use to. Since most people in the West's exposure to the genre has been Fate/Zero, most people don't know the whole setting. Playing a Servant is much easier. Being a good Master would be very rewarding for a player, and I would definitely play one if I knew enough about the setting. Just seems like you have to be that much more engrained and knowledgeable in it.
I feel you there. I've been RPing since 6th grade, and I outgrew the OP and cliche RP characters a while ago. Although, there's something to be said about playing a powerful, or otherwise cool, character in a different light. At this point in my roleplaying career, I'm more interested in contributing to the overall story than I am making sure my own character has a spotlight or does extremely well. I'd have no problem if Sun Wukong was the first servant to die, if it added to the story. Roleplaying is an interactive story telling experience, and should be treated as such. Not everyone is going to be Badassie McBadassface and wreck everything. If this advances like a "normal" Grail War, there can only be one TRUE winner.