I'm not a hugh Southee fan but I actually think there is less risk/more reward having him captain.
Kane is just a legend, playing like one of the greats at the moment. I wouldn't want to mess with that. Despite being a nice guy and a great player he doesn't strike me as a captain
I don't love Southee but he has a touch of charisma about him and is kind of like Bazza, the kind of guy who if he wasn't the captain would be the first guy going out down the pub drinking and tearing it up. Sometimes it's best to make these guys the captain to change their ways and set the example. I think that's exactly what happened in Baza's case. He figured he had to lead my example so stopped being the first guy down the pub, so the others thought if it's good enough for him to settle down its good enough for me.
Southee would have been his wing man and the second guy to head out
Kane is the sort of guy who would rather have a net then go down the pub. Not many in the team are like that.
And if it makes Southee more responsible in his batting and as a person I am all for it. Think it also could be the making of him as a bowler as well