I'm not sure what you mean by "swoop" but round, bowl-like helmets just look ... odd. Helmets with a bit of taper and shape to them look so much better.

That, and tapered helmets are supposed to be a little bit more aerodynamic and may offer a little bit more ventilation.

This, for example, is a nice-looking helmet ... and I'm going to have to see if it, or something like it, is available here in Australia.