I'm a little lost here. I've had my Xbox for a few years and I don't pay any monthly fees. I started at $49.99 for a year and now pay $59.99 a year. What exactly are you talking about, because I have no clue.
Xbox doesn't charge a monthly fee, unless you want to go a la carte on their Gold Membership, which is completely optional. I think it's fine that they charge to play online; they provide us with an awesome product, so why shouldn't they make more money from it?
I think they should lower it, but they have to pay for stuff to keep online running, also if you were them, and you had a product that everyone wanted with little competition, would you not do the same. I am not saying they are doing the right thing. I am just saying that you got to see it from their point of view too.
Technoupdate now brings up a great point, they don't have to worry too much because they don't have a lot of competition. Xbox live is where most of my friends play right now, so if I wasn't willing to pay, I'd simply be left out.
I have to admit that it's a smart business decision since the competition isn't there. If something new entered the arena that could take away Xbox customers, you'd be seeing a different situation. It's just the way the market seems to work. At the end of the day, it's about supply and demand.