I understand your point about the combat system. I personally am not a huge fan of this combat system as well but it works at least. For the pace of the combat, it actually isn't that slow after lv 50 and you have to think about the console players who can only play with controllers, 2.5 sec GCD makes sense.

There are many things I love about the game but this game does have some drawbacks; however everyone has a different taste, which you think is a flaw might make sense to others.