Nobody's denying you need the Bryan's, Ziggler's, Guerrero's and Benoit's.
Fact is, Ziggler/Bryan just won't be the top guy.
Guerrero wasn't. Benoit wasn't. Jericho wasn't. They had the Rock, Austin, Triple H, Kurt Angle and The Undertaker above them.
It's the same with Ziggler/Bryan. They are wonderful workers, the best in the ring in the WWE, technically gifted, but they don't have the same market appeal and commerciability.
Hence, Cena, Reigns, Lesnar and Orton will always prevail as constants. The best Bryan/Ziggler can hope for is getting the strap temporarily as part of a movement. I have the feeling Ambrose will go the same way.