Also a factor is that, even if we kinda guessed, Hogan vs. Sting actually being booked was never set in stone until close to Starrcade. There was always that "When will this finally happen?" tension.
The problem with Cena/Rock is that we KNOW the date, and it's so far away that nothing happening right now really matters that much with regard to it, unless they REALLY wanted to hammer home "Cena's quest to walk into WM as Champion" which would really bury everyone else even moreso than usual after a Cena feud.
--
Thank you, Eddie Guerrero.
http://i.neoseeker.com/n/2/nintendo_quality_seal.jpg