i played many rpg, they all have same things which i like: main char have 3-4 skill buttons & 2-3 skill build (change with hot key) so we can use effective skills in different situations.
Personally i played mage most of time with 3 skills to attack/ stun/ ... & 1 skill to def. I use Heal when farming to save pots, help team; Shield when going boss/ elite. It's a bit annoying to open menu & click to change skills xP

So IMO, it'll be great if we change skill builds system