Europe has been a growth market for Harley Davidson. V-Rods are popular bikes and if you look at the customizers over there like No Limits Customs, Ricks and R + R Customizing, you find the V-Rod is their favorite model. The Street was, if you believe Harley, heavily focus grouped with young European urban dwellers and the bike was unveiled in Italy at the big Intermot bike show. It is a natural market for it.
Btw, you don't see all that many Ducs or high end Aprilias on European streets. What you see are lot of low buck Japanese bikes many of which are being made off tooling for models long since discontinued in the US. Kawasaki sold a 550 cc shaft drive all-rounder in Europe for at least a decade after that engine, which originated on the GPZ 550 was no longer available in the US. Same with the Yamaha Seca 900, something the US never saw but was sold in Europe as a low cost alternative to something like a BMW. Most Europeans can't afford high end motorcycles and the Japanese and Italian manufacturers cater to that market with low priced but low content/quality models many of which you don't see in other markets. I have a feeling Harley did a lot of careful homework determining just how much people over there are willing to pay for and what they want out of a bike. A little Harley cachet may be just enough to get the customer to look away from a Japanese bike that costs a touch less but just doesn't have the Harley thing going on.
I live in a parallel universe but have a vacation home in reality.