While Season 7 was/is certainly the worst one of the NuWho for me because of those flaws you mentioned, I can't blame Smith for it. He is an exceptional Doctor...just not Tennant.
Eleven can do manic, he can jump around like a little boy riding a sugar high and hit the dark, dramatic tones necessary for a 900+ year old Timelord. But when he tries to do angry, he falls flat. Rory can do true rage far better than Eleven, just because he doesn't look and sound like he's throwing a tantrum. I almost laughed a few times while Eleven stomped around yelling at the sky back in "The Pandorica Opens".
But Ten? He could do Fury. While he was still manic and crazy and dramatic, the fury of the Timelord was utterly devastating. Eleven shakes his fist and hops around shouting at people and objects. Ten just glares at you. He gives you a look that could make Death himself blanch. He looks you dead in the eye while he utterly destroys you and everything you love, and it is terrifying in it's grandeur.
Grandeur isn't a prerequisite to be a Timelord, but Ten had that in spades.