Try this. Try riding up say a 6-8% grade on a Bosch or Yamaha 250W rated mid drive ebike while trying to maintain 20mph. You quickly discover that takes a significant rider effort to sustain that speed and I would argue that is a problem when using an ebike for urban mobility because if riding to work time is money so average speed matters a lot more that if you just ride for leisure or fitness (ie I don't want the ride time increased because I have to slow to 5mph to get up a hill like that if I don't want to get sweaty).
Sure front forks make an urban ebike rider a bit more comfortably, but I've had very high end forks on the ebikes I commute on (have the 2.5" x 27" Moto X tires I mentioned) and I can not tell a difference in ride quality unless I'm hit potholes or bumbs and that is just an occasional event - the forks add more cost and service than they do value on an urban mobility ebikes (check out most of the Stromer models and they don't have front forks and are consider by most to be the best urban mobility ebikes on the market).
I think a belt getting shredded on an urban mobility ebikes would be a very very rare event such that the lack of servicing is a big bonus. You are right that needing an IGH for a belt is a luxury. Sure derailleurs perform just fine but there is the risk of a lot of wear and chain stretch if the ebike has a high torque mid drive like the Bafang Ultra (sadly that motor is not being integrated on any urban mobility ebikes currently - Sondors had 2 models but not out of business).
