Basically, if I’m going to list the things that, in my opinion, detracted from the World of Warcraft experience it’s:
• No flying mounts
• No LFD (keep the LFG tool in-game that basically allows us to post parties and whisper leaders)
• No LFR (instead, add a comparable difficulty with flex numbers and allow people to use LFG tool, see above)
• Bring back talent trees
• Remove homogenization completely sans required role specific abilities ie taunt, resurrect, etc
• Reduce the number of available portals in-game
• Add a minor gold fee for changing specs outside of rested areas
• Bring back all stats for pieces of gear
• Reduce the amount of copy + paste gear from dungeons and raids. Unique drops are more fun to loot.
• Bring back weapon skill
• Bring back equip bonuses to include hit/crit, AP/SP
• increase the amount of threat healing and DPSing causes
Regarding a hybrid tax, I believe the game would be better served if individual specialization were balanced and made to be useful. For instance, a Retribution should cause respectable damage, be able to off-heal a limited amount, and bring good utility and buffs. I would not asked for gimped specs or OP gods. Abilities could still be limited by spec, to a certain degree.