I would have no problem with Blizz implementing these^ again. I would even take #9 a bit further and remove flying mount completely.3. Ranged weapons will once again need to be ranged. a 10 yard dead zone will be re-implemented.
6. Attunements and Keys will be added back into Heroics. If you do not have a key, or a party member with one, you are out of luck.
7. Simple Wood and Flint & Tinder are once again needed to make fire.
8. Spell reagents will be re-implemented
9. Flight will be removed from Azeroth but remain in the newer territories to provide more old world immersion
10. Samantha Swifthoof will be returned to the path in Stranglethorn Vale
11. Certain quest mobs will be given their elite status back and will require a group to kill them.
12. Low level dungeons will get patrols once more who will respawn and can come up behind players without warning
13. Guild perks will be removed
14. Mining, Skinning, and Herbing all have a chance to fail when trying and will once again only give 1 item at a time up to a total of 3.
17. Paladins, Warlocks, Druids, and Shaman no longer get special animals and mounts automatically. There is once again a quest chain to accomplish these means.
19. Each class Pet will again require a quest to complete in order to learn how to summon their pet.
20. Training is no longer automatic. You must once again visit your class trainer.
21. Pet trainers will be included in the afore mentioned.
24. Rogues will again be making poisons and applying them as they learn them.
25. Paladins will be removed from the Horde as Shaman will be removed from the Alliance. Too much class/faction homogenization.