Because he hates what it entails, i.e. it requires a different mentality where you focus on defending a position rather than attacking. That’s not who he is, so the team give him the freedom to race how he chooses. As he backs it up with wins, the sponsors are happy.
That and his weight... he's said that he had an offseason where he put on some weight (dunno if it was the one after the Giro, or one after that) and has never been able to get it back off again without a large drop in power.
Because he hates what it entails, i.e. it requires a different mentality where you focus on defending a position rather than attacking. That’s not who he is, so the team give him the freedom to race how he chooses. As he backs it up with wins, the sponsors are happy.