Yes, I know that. But you also don't have to pay if you want to use your apps such as Netflix or Hulu Plus, whereas with Xbox you have to, even though you already pay a monthly subscription fee to those aforementioned services. Therefore, it makes no sense to have to pay microsoft a monthly fee for the privelege of watching Netflix on your 360, that you already pay a monthly fee to Netflix for, anyway.
You said yourself that you were going to get one eventually, so what's the difference?