1. Less passives from abilities.
The "pruning" was terrible. Classes effectively kept everything but now it all applies automatically.
2. Less homogeneity between classes/specs.
Instead of everyone having every debuff at 10% power, everyone should have one debuff at 50% power or 2 debuffs at 30% power.
3. More resources management.
Most classes barely have to even manage their resources. I liked the old days where your rotation would be a compromise between more dmg / high resource cost or average dmg / low resource cost.
4. Less cooldowns with less power.
Whats the point of having 3 dmg cooldowns but effectively just popping all of them at once so that you deal 300% more damage? It just feels like you are weak without cooldowns.
5. Stronger white / base rotation damage.
That may seem casual friendly, but that's what will really differentiate a good and bad player; the ability to pump just a little extra damage all the time vs all your dmg during your cooldowns, all the while managing your ressources.
6. Free global cooldowns.
Why is it so necessary to fill every cooldown? Bring back free GCDs in rotations. This will also have the effect of giving good players an edge since they won't try to fill every GCD leading to resource management.
7. New talent system.
Why not do a compromise between the old trees and the new? Every level, you get to boost a small perk (1% stun resist, 1% crit, etc) and every 15-20, you get a big talent. This could also help hybrids make a small comeback.
8. Hybrids.
Ideally find a way to bring back hybrids WITHOUT the use of cooldowns. Being able to throw an effective heal between 2 damage casts was a great feeling.
9. Healer damage.
Healer damage has been terrible for a few expansions. There should be a way for healers to deal better damage, but at the cost of being mana inefficient (vs the current state of terrible damage at no cost).
10. Instants should suck.
Instant damage and CCs should be weaker (lower damage, smaller durations, bigger cooldowns, low range and/or high resource requirements)
11. Slows and gap closers.
Not everyone needs these. Currently, positioning has little value since everyone can get to their target easily. Make people run more; watch who sucks at positioning crumble. Obviously more pvp oriented, but great way to differentiate a good or bad player in pve.
12. Bring back real leveling.
The total leveling time should be 3-4 weeks, not 3-4 days. Heirlooms need to be much weaker. Dungeons shouldn't give 4 levels a pop. Open world mobs should be harder and open world quests should give more xp so that you don't outlevel a quest line within 10 minutes and need to change zone. Whats the point of the whole quest revamp Blizz did if nobody actually levels that way.