Many W/C engines are really ugly, and are covered with lots of tupperware. "Our bike for example". What makes a Harley is the fact that the engine is completely visible.
And therein lies the issue with HD 45 degree V twin. It is more about the looks, sound, and feel than the actual ride (which is loud, vibrationy, inefficient, less reliable, and poor performing). HD works very hard, at all costs and compromises, to try and retain the exact things that make it ancient technology while slowly adding a little modern technology to bring it up to where bikes might have been 30 years ago (or is that too modern?). Certainly not all, but many (perhaps even most) HD owners have a HD for exactly that reason- image.
I much prefer something that works and performs well, while also being affordable, reliable, efficient, smooth, powerful, and comfortable. I don't need to see (or hear) a flashy, exposed, chrome-encrusted engine to enjoy my ride. Besides, I think a slick exterior is not only more pleasing, but a lot easier to keep clean!
To each his own!