Mazda won the 24 Hours of LeMans in 1991 with a 4 rotor, 2.6L engine that produced over 700 HP at 9000 RPM's. This was a normally asperated engine.

Rotory's make a lot of power, and at one time GM had looked at the possibility of using one in the Corvette and the Vega was also supposed to (and was designed to) get a rotory. The two big issues with a rotory are poor fuel mileage and keeping emissions in check. With corporated fuel economy standards and strict emissions requirements, the engine is not practicle in large volume cars (and the RX-8 can hardly be called high volume).

As for rotory's being better than a V-8, it certainly was in France in 1991. But unless the displacement is increased, it won't make the type of power Americans are used to. As also mentioned, these engines are more expensive to build. In many ways though, these are not that bad to rebuild. When a rebuild basically means replacing the seals, this isn't that bad. But overheating one will blow the seals. Oiling issues in turbo applications have been problems in the past as well (see the last RX-7).