One thing about healing i enjoyed as well (i dont heal anymore). As a tank now, nothing annoys me more than getting the boss to 15%, looking at my healers' mana and everyone is on 45-60%, and ppl start to die to sustained damage (not failed mechanics). To me, it was just lazy ass healers and no communication - everyone focused on the tank instead of someone raid healing, or just general shit play. Then when i question it and someone says "being careful with mana" - fucker what the fuck you saving it for? we dead? how more pressing could the need for heals be?
As for the second part, what i dont EVER want to see the return of is dps downtime where they just have to auto attack for a while to regain mana. The way hunters worked was fantastic, and if every mana class had a similar mechanic (not identical) that would be swell. TAP was always good too, sacrificing some hp for some mana is a cool mechanic. I liked evocation as well, thats pretty cool - always obvious to see which mages knew the fights and which didnt - the good ones got a full evo cast in during a safe period, the shit mages cast it whenever and would have it interupted and wasted.
Ele could have a totem, Druids innervate, Spriest could do away with mana altogether with the current system imo. I guess the issue blizzard have is if it just becomes a standard part of your rotation, why have it at all? If you can easily mitigate the lost mana, why have it as a mechanic?
Smuggler was my main in SWTOR and it was fucking horrible. If you screwed up your rotation, you were punished with BORING and slow gameplay - less dps would have been ok, but nope, it literally slowed the rotation right down and made it horribly boring.