I mean ... I don't know about your experience with this kind of thing but, have you ever tried performing skills like this IRL?
You can't fire off things in such a way. And a -lot- of the skills have animations that last for the majority of their respective cooldown times, and look really weird when you use oGCD skills between them. (Yay going from a handstand to shoulder bash instantaneously!)

Which brings me to another point: The "fluidity" and "pace" of melee classes comes from the ability to easily inter-weave their Abilities between their Weaponskills, without causing any GCD-clipping (unless you're a ninja and have laggy 'net). Ever notice how your next Fire gets a small delay when you use Raging Strikes? None of that horrible standing around silliness with using Blood for Blood and Chaos Thrust, or Duality and Aeolian Edge, or Berserk and .........