It's not up to the resellers. Their job is to provide what customers want. If the customers don't want XP N, that's all the resellers need to know.
Somewhat of a canard there. Both products are essentially the same. The only diff that I can see is that one has WMP and the other doesn't. Downloading WMP (if it is free) or providing a free disk with it upon request doesn't sound like a terribly big deal to me.