I can't think of a single reason I would want to connect a mouse to a phone, but I guess it does have some cool factor. I really liked the look of that launcher though, so I went digging for it as I hadn't seen it before. Turns out our Phil reviewed it HERE back in March. Too bad it's 15 bucks (or was at least).
The only reason I could think of is if the phone was hooked up to the tv and was out of reach, would allow you to select videos from the comfort of your couch. Though for the most part, I agree, no real reason I would want to do that.