Because ratings means everything in the business.That is how WWE stays relevant on TV.
Ratings = cash .WWE aint ROH,indy company.
Among active roster Guan Sena is the king of ratings,despite what your personal opinion over Cena's drawing power may be.Big Show is a bigger draw than Punk.
Punk's antics on RAW may be the best entertainment available on TV for you but there are millions and millions out there who'll find Punk's whinny ass too boring to endure .As far as ratings is concerned,Phil cant even hold Guan Sena's jockstraps so to speak
Essentially,Boring shows = low ratings .Entertainment = Good ratings .
Raw is CM punk = low ratings