Lots of good post here, I would like to see "Veteran Rewards". CoH had these and so do many games now, Guild Wars 2 the current MMo I have been playing for 5 years does this by dishing out "Birthday Rewards" to characters based on creation date. (While GW2 failed in my opinion) I do enjoy and log into games that give better rewards to the players who have been with them through the years. I feel most games let me down because I expect rewards like Coh had...
Rewards that were not overpowered but made Quality of Life better or leveling a new character easier. Such as account travel powers/team recall(teleport)/rocket packs/melee powers(I remember choosing between the Axe and Maul, each had their perks)/Auras/Capes/So many more.
The nostalgia from playing a game and being rewarded for your time invested is a really nice feeling. Some people dont like this idea because new players cannot become equal, but I stopped putting money into GW2 mostly for this reason ALONE. I started to feel that new players were getting rewarded (With instant Level Booster and stuff that only filled my storage because it was useless to someone with maxed out characters and equipment) and treated better then the people who have been there a while. After all, its always the dedicated people who keep the games going during the good and bad times.
Depth, Story, Combat, Customization(Especially custom colored power-sets), Travel Powers(I could spend days just superjumping and flying around cities showing off my cape), Teams, Sidekicks, Quest and Radio Missions, New areas(Maps/Dungeons), New Powers, all these and more.