Dealer network is one of the things I think about when I'm considering which motorcycle I might buy. There is at least one Big 4 dealer shop in most decent sized towns, so if I was on a trip and something really went wrong, I shouldn't be more than 100 miles from the closest shop that could help me, even if it wasn't the exact brand.
Aprilia and other Italian brands, on the other hand, who knows. The local Ducati and Triumph shop in Akron closed a couple years ago, and as far as I know the closest Duc shops are in Columbus and Pittsburgh. Not enticing prospects if I bought a new bike and needed warranty work, especially since I don't own a trailer to get the bike there if necessary.
By the way, the local Big 4 dealer here - a large one - also sells Aprilia.