Life, Doctor Who & Combom: Christopher Eccleston Explains Why He Left Doctor Who: I left the following comment,
It is possible that the politics went higher up than RTD and Julie Gardner. Remember the BBC still had strong memories of the 1996 failure to reboot, as well as there are always those within the Beeb that simply hate the show no matter what its international appeal. Grade didn't act alone in 1985, even if that's the historical reputation he's given. So really I think RTD and Gardner were on CE's side trying to protect him from BBC higher-level politics, especially those that wanted a more "dashing" leading man.
Granted, CE's attractive (and hell, I can say that and I'm straight), but has a very different charisma in his character - he has to act through his looks (and does so brilliantly) rather than DT who can take advantage of his more comforting appearance. Some in the BBC (those who hire for Eastenders, or see the looks of those the competition gets on Coronation Street) saw a less physically perfect leading man as a detriment.
I also think most of this played out long before the first episode made it to the air and CE and RTD had the massive success they did. If CE had to feel like he had to defend himself in spite of that success, well, there's better things to do with one's life than argue with the BBC.