Because he is no Jean Todt. Think about all the mishaps the team had last year and this year. Like the refuelling fiasco with Massa or the missed opportunities to advance into Q3. Or the overall decision to go with KERS. The buck stops at the top. His co-manager has already been relegated back to Maranello. He might be next and I wouldn't miss him.
I'm not so sure, because he already offered to resign so.. If they really wanted to fire him they would have already, so they know he is capable. But none the less he needs to prove himself more.
JT offered to resign a few times too...But they dismissed it. Anyhow, there's improvements this past 2-3 races...so we'll see...