Yes, it seemed unusual at first reading but when you think about it, it definitely makes sense.
The more ways there are for people to hook into XBox Live, the better that is for Microsoft. Insisting that the apps are free just increases the desirability of XBox Live. Of course the fact that to use it and access it you have to have an XBox Live account and pay the subscription fee doesn't hurt at all.
And if anyone can tell me how to get OFF the XBox newsletter I'd greatly appreciate it, I've been trying for 3 years now to get them to stop sending me that blasted newsletter. No matter what I've done the sucker just keeps showing up day after day after day.......