I have no problem with the Doctor saving Jackson Lake's son in fact I liked how he did it.
I like the concept of "The Next Doctor" a lot. I think RTD's execution left a lot to be desired -- and resulted in a deeply flawed story.
Davies really needed another draft or two -- and a less sycophantic retinue around him who could be critical -- because I think "TND" would have been easily fixable. Have Lake play a role in the climax, rather than standing around as a passive observer. Have Lake, not the Doctor, save his son. Have Lake discover that, while he's
not the Doctor, he can still
be a hero.
And the biggie? Put Jackson Lake in the damn balloon. I thought it was fantastic that Lake had built himself a TARDIS. He, not the Doctor, should have had the opportunity to use it.
"The Next Doctor" is an episode of two halves -- there's the Cybermen plot and there's the Jackson Lake plot. Of the two, the Jackson Lake plot is the more interesting, but once it's resolved the episode loses a lot of its energy. Had Davies found a way to keep Jackson Lake involved dramatically at the climax, the episode would have been genius.
And when there's a multi-Doctor story in two years? I don't care one way or the other if Eccleston comes back. But I definitely want David Morrissey back.