Maybe it's because Smith actually acts like a Time Lord, and like someone who's actually clever, instead of an irritating twat who can't stand still without running around and SHOUTING AT THE TOP OF HIS VOICE ABOUT STUPID TIMEY WIMEY SHIT.
Fuck David Tennant. I only sat through his inane blathering hoping the new guy would be better. If they'd written Smith the same way, I'd have been out.
As I recall Tennant only used the words TIme Wimey in stories written by Moffat.

I think it was very professional and genuinely darned nice of him to say that. It's good to know he's enjoying a measure of success after his tenure in Who and that he's still such an obvious booster and fan of the show.