Initially, I was kind of upset Dolph won, but after thinking about it, it was a good call. Not the best call, but a good one. Miz kind of had to lose the title to Dolph because there was no one else on Smackdown he could lose it to. Smackdown's midcard is anemic right now. Everyone he could have conceivably lost it to - Crews, Corbin, Swagger, Hawkins (I guess), Slater once Rhyno dips out - are clearly not on his level and would have made him look even weaker than losing to Dolph. And if you bring someone from the main event down to take it, you risk Rusev'ing him.
This way Dolph, in his new role as "underdog babyface trying to prove himself," can be used to help build the aforementioned dudes. Meanwhile, Miz can feud with Dean or Orton (aka, the two guys currently on the lower rungs of the main event ladder) to get himself into that picture if that's the aim.
Obviously, the best call would have been an NXT call up or taking an upper midcarder from Raw. But if they weren't willing to do those things, this was still a good choice.