Blizzard could make a unique question once a day, where only one person could collect it and get a special item. Doesn't have to be an UBER item, maybe even something that does NOTHING, but looks good on you.
I think they need to focus a lot more on the Roleplaying side is all.
I.e. Pay more attention to the little details, make it able to sit down on chairs perhaps, or even make your own design for a clan cape. Maybe follow a storyline where you can become a vampire, then NPC's don't like you enough to sell you stuff, so you must go to vampir.... yeah, you get the idea.
I would much rather run around the world roleplaying then leveling.
Infact a world without roleplay usually ONLY involves noobs leveling... as shown such;
This is going to be a mix of what I have seen on the site and what is in my own head.
First of all, I know a lot of you aren't going to like the idea of taking D2 out of the 2d image, but as I've said, I really don't think the game can grow much if it is still indeed stuck in that phase. Perhaps the option to have a number of views, be it traditional 2d style, first person, third person, ect. ect.
In my view character creation would vary with everything. Hair type, hair color, eye type, eye color, face structure, body build, skin color, hight, weight, width, ect. ect.
This should make it as personal as possible. Along with this I think clothes should be worn OVER the armor, not visa versa. So your appearance has nothing to do with your armor, but rather the clothes you wear, and could buy.
I think you should be able to pick almost ANYTHING up, be it candles for light, then equip it in one hand, or chairs, ect. ect. ect.
I would focus a lot more on the roleplaying aspect.
I think there should be servers up all the time, a few big ones, not a max of eight people. With enough money, or perhaps hours online, or even a mix of both (Maybe ladder rank) you should be able to buy your own house. Only you can open and close the door. (This idea is a bit out there, I don't expect that to be implemented, maybe a item that when you press it, it lays the house down, so if the big server thing is out of the question, you can just lay it down every game for a bit of fun).
I think there should be one big world, not acts, so you have to walk from place to place, perhaps you can buy horses or wolves to ride on? I just think it should be an incorperated place.
Villages/Towns/Citys/Empires should be HUGE, attacking should be permitted so there can be missions inside the citys. You should be able to join a guild and clan.
Guilds would be to do with the NPC, every week you might get a new mission you could do. If you buy the game a year into it, you would then have hundreds of missions to do off the side of the main story.
Clans would be player organised groups. Speaks for itself.
Perhaps not even a main story, more just lots of little ones.
Remember all this is assuming we have a few (Maybe 20) big servers that are always up, not hundreds of tiny ones that go up and close every five minutes. Also assuming this is first person, it could be done 2D style, but at the VERY least I would want the option to spin the camera around to different angles.