It's a lot more difficult to hold a full model m on your lap if you sit in a big comfy chair to surf, watch shows, play games, read, program, draw, paint, ect, and don't have a desk. Same reason I love TBE's, siig minitouches, and think normal mice are stupid. If you spend 14-18 hours a day on computers of one type or another it's stupid to sit at a desk.