Other than not wanting the hassle of shifting his life to another country or place (woulnd't need to do that if he want to Chelsea though), I can't think why he would want to stay, no CL, he wasn't played up front in the latter stages of the season despite his success there, he showed his discontent and we've been going backwards and don't seem willing to compete for the top players.

His age and the fact he's in the prime of his career will no doubt play a part too. You could argue he might wait till next summer when he's free of course.