One of his recently released apps is definitely for watch aficionados. High-end watches are a new interest/hobby that he picked up after he inherited a Rolex from his father. It's something that he enjoys and pursues with a passion.
Yeah, I agree with you, this app isn't going to change the world. However, I think he's taking the right approach. He's at a point where he's earned his right/freedom to work on what he wants. If he so happens to find an opportunity for an underserved niche in something that he's genuinely passionate about, I'd argue that's definitely the approach to take. Go with that and see where it leads.
Everyone (prob including himself) is expecting him to put out a home run product now. He seems "due" for it. But if he comes out swinging for the fences, which I think he kinda did with Milk, there's a good chance that all parties will be disappointed because regardless of who you are, those home runs are really hard to come by, and even for someone like Kevin Rose, still very unlikely. I think if he follows these sorts of opportunities where his passion lies, he'll create a succession of hits that may eventually lead to his home run. Who knows, there's obviously no science to this, but that's the approach I would, and do, take.