Well even tho they have promised changes, this is the 7th or so incarnation of a combat system, it seems for whatever reason, they have yet to come up with a combat system that they can all agree too, in my opinion the combat system they had in 1.0 was far superior to the one we had in Beta up to Now! Removing the limits of GCD so that you use other skills while you wait for your skills in cool down to be up, seems like a wrong approach, since the problem with the combat system was not one of long cool downs, rather it was of the system and the encounters being way to easy, you really did not need to think of a rotation at no point at all during beta, you just spammed 1-2 or 1-1-1 and called it a day, also TP regeneration was a huge problem, you had basically infinite resource to use, with out a second thoght on managing it.
I did both dungeons in the beta, and none of them where even a challenge the first time i did them, as a lancer i had no problem getting aggro, i could burn the monster down, while the tank tanked another one easy, in case of a bad pull, if a monster aggroed the healer, i could get his attention, beat him, and still have well over half my health to kill whatever it was left standing, that is not a problem of GCD, but of encounter Design. Now with the freedom different GCD will give us, it will be even easier to do just that, unless they have drastically changed the encounters to be harder.... Which i guess we will have to wait and see.