I hate to say it, but that's going to be pretty standard for MMORPGs on Xbox Live. Live is your key to the service, and most games let you play peer-to-peer (using one Xbox as the "server"). MMORPGs, however, need a huge mass of central servers, and they need to keep those servers running. That's what the extra fees are for.
Now, if they can just roll that into what you're paying for Live when Live goes monthly, that would be more convenient. I don't think that will happen, though.