I think the problem is parts, service, and the fact that if someone wants a flashy italian bike, their first thought is Ducati. If Aprilia had a truly phenomenally better machine than Ducati, or on par with the Japanese bikes, we might see more popularity. I love the RSV Mille 1000 R, but I know if and when I wrecked it, it'd be insanely painful to get parts, and to pay for them.
Mototek here in Austin is pretty dedicated to Aprilias from what I understand, so their sales are probably better because of their reputation. FYI, this new forum is put on by the guys at Mototek. I haven't been down there yet, since I've only been in Austin about a year, and bike riding about 4 months, but I understand they have race nights and all kinds of good stuff. Definitely sounds like the place is worth checking out if you're interested in Aprilias, and Aprilia racing.
1997 Suzuki GSX-R 750
2000 Mitsubishi Eclipse GT