Marketing has always been Squenix's Achilles' heel's tendon's weak point. But in this case it's quite simple:

TESO has three hundred million Ameriland Fun Bucks behind it.
FFXIV does not.

If I had $300M to blow on another big-promise, no-delivery MMO, I'd throw money at advertising the beta for my game too. Still, I don't think FFXIV stands to gain anything by widely advertising its beta after the 1.0 incident. Unlike most betas, in which you are basically playing a demo, FFXIV must necessarily change between beta and retail. Meanwhile, TESO can ride the hype wagon all the way to release day; the beta itself is as much a promotional tool as the poster you saw at GAME.

If Squenix would spend any advertising dollars on FFXIV, I'd hope it would be for a full and complete game.