Cooldowns.... how modern. I guess it encourages more experimentation if your not worried about expending single use spells before resting, but.... that means we will definitely be getting a persistent skill bar at the bottom of screen somewhere. My hope is that they are stylized icons rather than full colour art of flames and screaming faces etc. The original games made very effective representations of spells and skills with their little icons. It will look much more stylish that way I think.
But if you don't have spell slots, spell memorization, and resting (all of which are core elements of D&D), and instead cooldowns (D:OS), how is this a D&D game? That's the question I have. Are they making a D&D game or are they making a D:OS game?