The second stage was done for aesthetic purposes. I hate cleaning spokes, so I went through SMT for wheels (highly recommend), where I also took the opportunity to widen the tires. The 150 front and 170 rear are the widest possible without requiring modifications.
The first stage was done for function. Larger tank so I could actually ride somewhere without needing to refill, handlebars with enough pullback to sit comfortably upright, and reduced reach seat to also make for a more comfortable ride.