The global cooldown is not going to change unless Square were to lose 90% of their playerbase and everyone's reasoning was "global cooldown was too long".

The game's combat was built around a 2.5 second global cooldown. Some of the animations almost take up the whole time. They'd have to revamp combat drastically to adjust to a 1s global cooldown. Animations would all be shorter(and would fire off so fast it would look ridiculous).

I thought I would hate the GCD after playing so many fast MMOs, but I was wrong. I love it. I wanted a slower paced combat system ala FFXI. Not AS slow as FFXI, but I didn't want a slower pace. Feels nice.