I started riding back in 1983, and owned a Suzuki GS1100 / GSX-R750, Kawasaki Ninja 650, and a Yamaha FZR1000, which were all inline 4's. Then I got a Ducati Superlight, which totally made me relearn how to ride on the same roads. Like has already been mentioned, with a twin, you have a lot more useable torque, so you're not shifting as often, and can carry more extrance and exit speed thru the corners. Plus the mass of the engine is less and usually lower, so they're narrower and easier to toss around.
After the Ducati, I had a Moto Guzzi 1100 Sport / V50 / Eldorado LAPD / EV11 / Jackal. Also in the mix was a BMW 650LS, all twins, so I was sold on v-twins at that point. Right now, I have a Cagiva 650 Alazzurra v-twin, Yamaha Bolt v-twin, and the CB650. Riding the Cagiva and CB650 back to back is like apples and oranges. The CB650 has a much stronger top end rush, it just wails all the way to redline. The Cagiva, on the other hand, accelerates like a freight train, nothing dramatic, it just goes to it's 8K redline. But it will outhandle the CB easily on the same roads, because of it's lighter weight and more useable torque.
But as for the original hypothesis on the first post, v-twins are definitely a minority in today's motorcycle market. There are a LOT more inline 4 models out there than v-twins. Now some makers pretty much offer only twins, like Ducati, Moto Guzzi, Harley, Victory, etc. But if you look at all the models that are offered from all the manufacturers, inline 4s will greatly outnumber v-twins.