At least a small legitimate part of the reason for buying off the marketboard instead is because NPC merchants don't sell High Quality gear. (From all I've seen so far) And HQ is notably better than Normal Quality gear. Of course, being HQ, it's of course going to be more pricy.

But with the prices they're currently at? Yeah, I'll admit, I try not to think about it too much either, lol. It's probably the hype train.