Rose is a masterstroke. Best intro for any new fan, period.
Which makes his decision to rewrite The Reality War genuinely baffling. Why does it have to end with a regeneration? Why not replicate Survival so that, the next start can be as surprising as Rose was?
I think his argument was that having the regeneration and Billie pop up was a shock (though obviously not to anyone on this forum) and a mystery, it prompted continuing interest in the show rather than going with something more limp. I'm guessing as well that Ncuti made it clear he definitely wanted out (in a Gareth Thomas "use more squibs" kinda way).
I'm not saying I agree with the choice (I think Chibnall's original idea of a regeneration but you don't see who the Doctor regenerates into is better) but I do understand the logic and it does fit with RTD's personality because he is such a showman.
"Roll up! Roll up! You'd better hope the show comes back if you want to find out why the Doctor has regenerated into Billie!"
No real skin in the game, I genuinely believe RTD's PT Barnum, Greatest Showman, in your face, promotion of the show has both helped and hindered the show in different ways and at different times.
I'll always prefer Moffat's smoke and mirrors/stage magician approach, but I do appreciate RTD's strengths (and acknowledge his weaknesses!)