As for the history and storyline part, the factions will do the trick with this baby. Quests and such being part of the journey, what faction your'e in determines the quests and jobs you can take.
Quests, this is a really important part. Many games have quests which just have you do things which are redundant, keel rats and get their tails I mean..c'mon..who the hell needs 20 rat tails from every single player (Over millions) for anything!? The Rat whip?
Will Quests be more unusual, less frequent? Quest NPCs, some may be the he usual..stand there with a ! above their heads (Wow ripoff<The storyline part is based upon these guys.>). most should however be NPCs that spawn randomly, all over the world and it would be lucky for a player to find them. Rewards shouldn't be menial either, think of it as finding an uber item drop but you have to do this and that and this and that before you can get it.
Once someone has recieved a quest from that NPC or sometimes items, he goes poof so that other players do not find him and he usually leaves you with a message of how to contact him (Usually by completing the quest then arriving at a certain X,Y coordinates, only then does he appear).
This can fit into the storylines as well and I know how to...just the details I don't think anyone wants to read as it can go un forever.
As for the customization at the beginning, the template thing. People really want races because of how they look, it's the raw essence. Why not just humans BUT if you really want something different, maybe stripes markings pointed-ears red-eyes but nothing too appalling. NO WINGS! You'd be better off as a fly. Plus, wings are for sissies.
That's where another use of guilds come in again, maybe a bunch of people with stripes may come together and start calling themselves 'Tigers'? The term race and guilds doesn't exist, guilding is merely a function which congregates people and everyone is under the term 'People'.
With that, I end my case and requests that the jury make a FAIR, JUSTIFIED descision that you all can achieve...by digging deep down into your own hearts. Are my words fallony, or merely the speech of another who sympathizes with my case? *Hic...too much booze*