It doesn't seem like too bad an idea to me. A lot of people are screaming 'pay 2 win' over this, but win what? You can buy some of the best crafted gear in the game? Who cares? It's good enough to get around in most anything you'd want to do, but so is just about anything else. It's generally noticeably worse than tome gear which is already easy to get. The only place where gil can thrust you to very nearly the highest tier is crafting and gathering, but there are still some things you actually have to do yourself to get your main hand equipment.

It doesn't add any gil to the system so no inflation. If it did anything to detract from RMT activity it would actually slow inflation or cause minor deflation. If you weren't interested in the system at all then it should have absolutely no effect on you. You'd have no reason to do anything differently and even if others bought and sold game time the gil circulating through the economy would be static (relative to this change), so you'd barely notice it was happening. The most dramatic impact it might make is reshuffling gil a bit. Players with little time might buy extra game time to sell to players with more time (and less money). However, they'd largely turn around and give the gil back to those same players in exchange for high end crafted gear or dump it down a gil sink (like a house).