That's because it was all supposed to be a secret until the BBC later leaked the info. They first said that Eccleston didn't want to be typecast. After a big fan backlash against him, they came out and admitted that he was only supposed to do one series. Why do you think Tennant did the narration for the Doctor Who Confidential before the premier?

whomod said: I generally don't like it when people decide to play by the rules against people who don't play by the rules.
It tends to put you immediately at a disadvantage and IMO is a sign of true weakness.
This is true both in politics and on the internet."

Our Friendly Neighborhood Ray-man said: "no, the doctor's right. besides, he has seniority."