1000cc is 1000cc! Run what ya brung!
This is not true. The configurations (V-twin vs I4) may offer similar torque levels, but the hp differences can be huige, not to mention the rev limits. The 1000cc I4 have to be restricted or they would blow everything away with the right racer.
The hp claims of the 998 Duc were someting like 184hp, where the GSXR 1000 superbikes are something like 200hp. Unrestricted, and with a seemingly unlimited budget, I'm sure 200hp would be just a minimum, then all of the V-twins would be at a total loss, which would kill Ducati's market share.
Why don't we ask the real question? Why does the AMA Superbike series have the most parity in brands and very close competition at all of the tracks. Obviously the AMA's former formula worked quite well to give all of the brands and engine configurations a chance at winning on any given Sunday. I'm sure this enhanced showroom sales in the US as well. However, if you were not racing a Duc. in the British or World SBK series, you didn't stand much of a chance at even finishing in the top five, unless Honda wanted to lay claim to another title chase. I think it's really a sign of where companies believe their strongest markets are, and how much bang for the buck they get for their racing programs.
Let's also face the fact that customers with $82k can buy a privateer Duc superbike, albeit last years works machine, with a good assortment of "go-fast" parts. Will Honda, Yamaha or Suzuki sell the average privateer their "A" or "B" kit parts, even if you have the money? Probably not. Furthermore, there are ton of aftermarket parts manufacturers for Duc-ware, which also help enhance the performance of Joe-Sunday's bike.
In the States, Honda, Yamaha, Suzuki and Kawasaki have the money to pay riders and provide bikes without the supplemental efforts of a local team. If Ducati had a stronger presence in the US, like a manufacturing facility, then I am sure the bar would be raised. It comes down to resources. Chanlder did well last year in the US, Ben Bostrom and Anthony Gobert did well several years ago on the Duc. Hopefully they can show some dominance in the series this year, although the Bostrom's, Mladin and Yates are going to be hard to beat.