donkey.logic
The way I figure it, he only got his number because it shows Seven regenerating into him. If he'd just shown up like Nine does I doubt he'd be counted as a proper Doctor, but since we see him regenerating we can't deny it.

That's probably why he's lumped with the classics too, though he's plainly not. Eight is just some weird amoeba like entity floating in the void of the 90s.

But he has floofy hair and voice pr0n so all is forgiven.

3nodding Exactly. My dad said that their one mistake was showing the regen scene, which makes it canon. Otherwise they could have gotten maybe a series or two out of Eight, but since it was just a movie it kinda flopped.... confused
And then we had a lapse of Who. stare