Oh don't get me wrong. Hammers to nails Danzo is a well written and Solid Character. For the very reasons you just mentioned. The fact that, obviously he wasn't always this way is what intrigues many of his fans. At what point did the Danzo we know come to be was probably around the time Tobirama picked Hiruzen to be the next Hokage.
My point is you can't really say the village is or would be better off with Danzo as Hokage, simply because his conviction or "will of Fire" is strong. And the mistakes as we call them he doesn't see them as mistakes. He thinks what he did was for the good of the village. It's that twisted logic that makes him so great in my opinion.
I'm sorry I know I was a bit harsh with Karin's character, but honestly it's not the fact that she has an infatuation with Sasuke that bothers me. Most of the K11 girls are into him as well even now.
My problem with her is how quickly she forgave him. Sure he saved her life....
...But he also nearly killed her so he could get at Danzo. But aesthetically, I don't find her overall design very appealing or intersting, nor do I find her bi-polar mood swings all that funny even though Iknow they are for comedic value.
Something like that, no matter the circumstances of your life, are not so easily forgiven. This is all just my opinion of course. I hav no qualms with those who are fans o hers. After all, I'm a fan of Sakura's XD