Thanks guys
DannyG,
Its becuase Ducati and Aprilia use V-twin (V2) engines, while the leading performance bikes like Suzuki, Honda, Yamaha, Kawas, etc use inline-4 engines (L4) which are much superior perfromance wise. The Inline-4's are lighter bikes with more power, so performance wise they are in another level. For example, in last years MASTERBIKE (a supertest conducted at a track by over a dozen magazine around the world and over a dozen profesional and press riders, very scientifically conducted to compare all sportbikes of that year), the Yamaha R6 which is only 600cc (inline-4) matched that 1000cc Ducati 999S around the track, and the Yamaha with only 600cc, less HP and half the pricetag. Its not even the fastest of the V-Twins, the Aprilia has always beaten the equivalent Duc around the track in the MARETRBIKE. Another thing is that they are very expensive and higher maintenance, and they have more issues.
BUT they have their charm and character, and they have fantastic sound, and ride a bit different so some people love them and cherrish them. Its a matter of personal taste really, but since inline-4's are faster, better fperforming, lowr priced, more reliable, etc. then they dominate the market and have the biggest following.
I'm a performance nut myself so for me I like the fastest at the track, sportiesst, beastiest bike, and that means a 1000cc inline-4 class bike, Suziki.