The fated day where I disagree with one of your takes. 
I’ve never been a fan of cooldowns in games that are rooted in ARPGs. Wicked is not fully rooted in ARPGs and I haven’t played a game similar to them such as V Rising. What I can say is cooldowns have usually felt too limiting and relegating players to a very passive playstyle.
Commonly in ARPGs, players run around waiting on cooldowns to nuke large clusters of enemies they’ve gathered during the cooldown period. It becomes a much lesser active playstyle and one that’s purely rotational rather than reactionary as well. It also takes away the feeling of investing a good amount into maximum Focus. You gather all this Focus and just let it out on a boss. I feel like a rush is taken from us with this.
I can understand the argument for runes such as buffs. Many of us now carry around a second weapon purely for runes with utility so we can place only offensive runes on our DPS weapon. I really want to have a Healer playstyle in the game, just like Evocator1000, and the second weapon that most carry essentially invalidates this idea. On the flip side, how do you make it so mages can still feel like mages? The basic Fireball still hits hard but now is behind a cooldown and mages are forced to go melee, more so than now.
To summarize:
Pros:
- Decreased reliance on secondary weapons for utility.
- More methodical gameplay.
Cons:
- Less feeling of power and control over it.
- Potentially limiting the mage fantasy.
- Potentially devolving into a waiting game for runes to come back.