It would be to much work. Since xptminer tends to be for a specific coin, and can only be used for their site. He have to make a new version of every coin someone wants to mine. He'd have an easier time setting up his own altcoin pool and charging a fee
Well there are 2 ways - either you hardcode the pool, or you hardcode the fee address. A hardcoded fee address going to cbuchner1 would of course mean that he needs to have his own specific address for each new coin... well but that's doable, isn't it?
doesn't sound very practical on coin launch... nor for solo mining... (put that way, you can't even choose what to mine...)