I think the main challenge with tab targeting is that it doesn’t really fit the way the game is currently built. Most of the abilitiess here are designed as skillshots that you aim with your cursor, not something you lock onto with a tab key. Like you mentioned, WoW had that predictable flow where an ability would land unless actively countered, but that kind of system would need a full rework of how abilities function here. It’s a completely different playstyle at that point. 
About the distance indicators, I get the idea behind it, but Im not sure how well it would work with the current camera setup. The POV here is much closer and more action-based than something like League, so I feel like adding more UI elements could just end up cluttering the screen, especially in the middle of fights.
This game feels a lot more reactive and fast paced, with a heavier focus on mechanical execution rather than preplanned strategy.
Totally respect the feedback though. Always cool to hear thoughts from someone with serious PvP experience.