Numbered, but in no particular order.
WWF Event Center: A place where workers could put themselves over with cheesy promos with really awesome backgrounds. Seriously, those backgrounds RULED.
Mid-card: WWE's current opinion of card build-up can be summed up as Main Event and everyone else. Problem with that is simple: Your Shawn Micheals', your Undertakers, Your Triple Hs, and Your Batistas aren't gonna be wrestling forever (except maybe the Triple Hs.). You need to groom someone for that role once they retire, or if they fall to injury. Also, good mid-carders can help get the crowd into the match as well. But, why should we care about a midcard if they can all get crushed by one guy?
Different Looking Wrestlers: Why the fuck is the WWE roster full of Tall, Muscular guys with short hair and a generic Tattoo on their arm? The only exceptions are the guys on top. The criteria suggested by Johnny Ace clearly doesn't work, especially when you consider that, of the biggest stars in WWE History, Only two people (Hulk Hogan and the Undertaker) meet the criteria. WHy should I give a shit about someone like Mike Knox, when I have seen a dozen guys on the WWE roster that look almost EXACTLY like him?
Programs that draw in the female fans: I'm not trying to sound gay or anything like that, but you can't focus on just one demographic. I'm sure the 18-34 year old male is important (I think that's the demographic), but you have to appeal to EVERYONE to get a successful program. The last time a program really worked on that level was the Matt Hardy-Edge feud, a feud that MADE Edge and has left Matt Hardy as Perenially over. Even that was botched. The Punk-Knox feud COULD have worked if they didn't drop the ball. The reuniting of Elizabeth and Savage from Wrestlemania 7 was huge because it got the female audience into the program.
Beyond just female fans, wrestling can reach across all demographics if booked properly.
Managers: Not every wrestler is a good talker. Sometimes they need someone to do the talking for them. That's the role of the Manager. Not every wrestler is going to be over on their own. Sometimes they need someone who is associated with heat, thus giving themselves heat by proxy. Again, that's the role of the Manager.