This is bizarre. The toast rack design is designed to be efficient in airport terminal space. Taking the 45 angle as a design you'd need to space the gates further apart leading to longer walks for passengers, bigger terminals, more building to heat and cool... etc etc etc. Sure if you've already got a big airport and a little plane you might do it a bit, but by not standardising you introduce new error paths and smacking one wingtip into another is really really expensive (as is the jet blast comment made earlier). In fact why not do away with the terminal gate completely and just have a big open space the aeroplane can taxi through...