Main eventers are main eventers period. It doesn't really matter where on any given card they are placed because they could easily close the next show. Card placement isn't as important as people make it seem.
Being in the first match used to be called "curtain jerking" and you were considered low level, now John Cena is in the first match on RAW, is he a "curtain jerker"? Fuck no.
Each show can only have one closer but multiple main events. The WHC is a main event title but it doesn't close PPVs generally but it closes SD and it closes SD house shows. Thus the guy who challenge for it are main eventers...they are apart of a main match on the card. Whether that match is 3rd, 1st, 7th etc doesn't even register, because card placement isn't what counts, what counts is the amount of time given to your match/segment and its level of importance.
I'm all for guys wanting titles because racking up titles should always be the goal. The way the E books things however is that some guys are "bigger/beyond" championships and don't need them. I suppose it creates opportunities for up-n-comers, but what is the point of 2 guys nobody cares about wrestling for a title? Especially when you have a bunch of over, credible talents that aren't doing anything. I'm not lobbying to put the IC strap on John Cena or anything but its a title he's never won, therefore its an avenue unexplored. Besides if you were to do something like that his opponent/match would already have instant heat. One person everybody loves (or in Cena's case hates) vs some up-n-comer trying to make a name for himself. Its a big time rub if nothing else. But instead we get Cena steamrolling the US Champion in 4 minutes....its nonsense, nothing good comes from that.
IMO the WWE only has 7 to 8 guys who are Main Eventors: Punk, Cena, Rock, Orton, HHH, Taker, Lesnar, and possibly Flair.
It has has 3 titles that can Main Event the WWE Championship, WHC, and if Booked Correctly the Tag Team Titles.
Guys like Miz, Bryan, Kane, Seamus, Christian, Del Rio, Show are only Main Eventers when they're in the title Mix. Although Seamus is on the verge on making the jump.
These guys would do fine going down and winning the IC or US Strap. No Cena doesn't need the IC belt. But Daniel Bryan or Christian could def. use it. The past few years we've seen Seamus, Jericho, Flair, Miz, Christian, Rey, JBL and Hart all going after the lesser titles and it didn't hurt them or the strap. I think this actually helps the mid card out.