You don't have to be a great wrestler to be entertaining to the common fan, though. Hulk Hogan is and always was a terrible wrestler and he's agrueably the most popular wrestler of all time. John Cena needs to have his character tweaked before having his in ring preformance tweaked if the WWE wants to earn more money.
In his defense, Cena's not too bad as long as his opponent is a good wrestler, i.e. Angle or Jericho. It's when they pair him up against the likes of Carlito or Snitsky that his flawed ring preformance shines through.