- The feel of a larger world.
No: i did not like the quests that would drag you all over the world as an infant player.
As to the feeling: I think Blizz is doing a good job trying to bring this back by making the large areas that we get in new expansions and by placing a non-fly rule when you first set out in the new expansions. But for the most part this is again nostalgia. Why? Because when I first started playing I had never played a game like this, which made it seem far huger, and I didn't know any of the content. Now I only get a short-lived version of the feeling when a new expansion pack comes out as it does not take that long to explore the new area. To bring this feeling back one would have to play a new game or erase one's memories of WoW altogether! Vanilla WoW won't bring it back as I know that content as well...
- More dramatic day to night changes.
This is a suggestion that has been made many times and is now finally being looked into! Yay! Sorry, but MMOs are supposed to be immersive... so WoW should not ever aim to lose such a thing!
- Realms were not as empty as they are now.
So there was a geater feel of the players around you and there was a higher chance of pvp action whilst you were questing.
This could have been easily fixed in 1 month's time in the way that SWtOR solved it. Do not make free transfers from overpopulated realms to lower populated realms. No one wants to move to a lower populated realm! It's madness! SWtOR made it work by making free transfers from low populated realms to higher populated realms. They filled up the higher populated realms and emptied the lower populated realms. They presented those who did this willingly with ingame rewards, and eventually forced everyone out of the lower populated realms into the higher populated ones. The result was practically no whining and only full realms, and much happier players.
However: WoW seems to be going on a completely different, but interesting path. It seems that the idea of realm transfers being the solution has been wiped from the table, and it is now all about making it so that it does not matter in the least which realm you are on. With Real ID invites, cross-realm BGs, cross-realm LFR and dungeon groups. Just Blizz: please finish the job by making the Auction House cross-realm and perhaps making guilds cross-realm. If you can do that then there really will be no disadvantage to being on a low populated realm, in fact you will create a small advantage towards being on a low populated realm when it comes to farming. This, however, will be short lived as people will be more willing to spread out across the realms as it will really not matter which realm you are on. Problem solved! Very interesting and well done!