There's other quality-of-life upgrades available in the gem store (real world money store) like infinite gathering tools and inventory expansions. That's what I spent my IRL money on. But yeah, not really accurate to call that a "power" improvement.

Can you buy fractals infusions or other equipment upgrades with gems or gold, or do you have to acquire them through fractal dailies? I never had enough friends to do the fractals content.