In my opinion, it makes sense that to play matchmaking in Halo or Call of duty, or even other online games you have to pay monthly. As well the price is not that much so I personally don't mind.
However the issue with the gold subscription comes with games like Phantasy Star Universe. I think that is what killed the game for me; a gold membership and a guardians lisence (monthly fee for PSU) seems to much. I have no problem paying for one or the other but, paying for both is hard, especially when I have student loans and stuff.
I wish that the gold subscription would pay for the service and the games you play online. So instead of for example buying a guardians lisence, part of what you pay for your gold membership went to that company directly. Of course that is not very feasible.