One part of what's driving cars to all look the same is mandated fuel-efficiency targets, which make aerodynamics a primary design factor that overrides nearly all others. Sacrificing any amount of aerodynamics is unlikely to happen under that regulatory environment.
This just isn't true.
It's very possible to make highly aerodynamic sedan, hatch and SUVs. Drag coefficients are available for most cars.
A bigger difference is detailing: things like mirrors make a huge difference.
In that case, estate cars would like a word with the current crop of SUVs