Just wondering why you can hold a bow attack and shoot whenever you want but you can't do the same with a sword/staff or whatever.

Because a bow's power attack is potential energy and a weapon's power attack is kinetic energy.

I am playing a Sorc, after 3 weeks of beta my conclusion is while leveling there is no good reason to take a destro staff over a bow until resource management and bonus dmg is being min/maxed in order to complete content. So endgame. I would prefer destro staff and will probably swap to one at 50(or max) but while leveling will be using a bow because of the difference in attacks.

Bow will do more damage up front with sneak attacks and early on / mid level it is better to draw from two pools rather than max damage on one. I have tried to say this before and people shot me down citing only exactly the endgame reasons. I expect the same again.

Really enjoyed bow fighting, especially with the close-in abilities enjoyed by a Night Blade.

I don't know why. That makes a bit of sense and lines up with my experience with bows thus far. After 15+ i have found myself using bow to start a fight then swapping to my melee config and lotus fan'ing into the mobs face.