Some players are really against any changes, because they want an authentic Classic experience, and I get that.
But what is wrong with just giving players options.
Here are a couple of things where I really think giving players options doesn't do any harm.
Using updated players models, including druid forms
It could be set up in a way where every player can individually choose if he or she wants to use old or new player models, and what druid forms he wants to use, and it's only visible to you. If you choose new player models, you see every player with new player models. If you choose old player models, you see every player with old player models. Completely independent of what other players choose. Some old models just look awful, and especially the druid bear form just looks horrible.
Now giving players the option what they want displayed on their own screen doesn't affect anybody else. I don't see how that would ruin the Classic experience. If you prefer old models, you can always use them. Nobody will force you.
AoE loot
I can not come up with a reason why that would be a bad thing. I've never seen anybody be nostalgic about having to loot every corpse individually. And if you do think it feels better, you can always turn AoE loot off.
Barbershop
I can not imagine how terrible it will feel to level my character to max level only to feel that I'd prefer a different haircut/color/face after all. The barbershop was one of the best additions to the game, and I've never heard anyone say that it killed the game. Many players will feel at some point that they would like to recustomize their characters, and starting over because of a bad haircut, or just having to endure a character appearance you don't like anymore are not good things. The option to have a barbershop, even if it is just an out of game service you can use for free, there is really nothing bad about having the option.
Some people will come out and say "if you don't want everything to be just like in Vanilla, you don't really want Vanilla". But where is the sense in that? Just because I've gotten used to better graphics over the years, doesn't mean I don't enjoy the gameplay of Vanilla. If I don't want to look at the old druid bear model, after we've gotten all these great updated models, that means I don't want to play Vanilla at all? Gnome females look gorgeous on live, but in Vanilla they look terrible. I've never played a female Gnome, until they updated the model.
Some people will say "just play on live if you like the graphics there better", but is this really fair? I wanna play Vanilla, because of the old content. Because of the old zones, the old quests, raiding Molten Core at a level that it is tuned towards, doing the Onyxia questline, doing all the old raids, getting into Naxxramas, seeing all the stuff that has been removed from the game. Experiencing all the classes the way they used to be. I actually enjoy quite a lot of the classes the way they used to be. Wanding on my warlock. The old talent trees. That's the point of Vanilla servers. But giving players options, that don't affect the experience of others in any way, can't possibly be a bad thing. It feels like some people have a cult-like attitude towards Classic servers that throws all logic and reason out of the window.