The bosshoss is also a production motorcycle and I will put it up against absolutely any japanese or any other production bike out there on a straight track. In fact you can even supercharge and put nitro on those bikes and it will still smoke them naturally aspirated and it won't get over 3000rpms. So you do understand that lower rpms the less stress and wear there is on a motor right? You als know the lower rpms produce less heat right? The reason those jap bikes are made to rev as high as they do is so they can try and match the raw power of the vtwins.
I am starting to wonder if you know anything about motorcycles beyond what you have learned from gixxer.com.
Boss Hoss's are so heavy that their quarter-mile times are pathetic. All they can do with all that power is light up their rear tire. A Boss Hoss is a great big piece of ridable jewelry, a toy, not a motorcycle.
And heat is not a problem for modern bikes, because they have that oh-so-new innovation, liquid cooling (it's only been around for 100 years or so). A new GSXR1000, straight off the showroom floor, will produce 150 RWHP from 999 cc. And that's EPA approved for emissions and sound. The reason they rev so high is because they can, and because you get high performance by getting a lot out of small package. There may be "no replacement for displacement", but you can take that too far, too.
Your comparisons with narrow-focus custom bikes with oversized engines (which, again, most riders would not want to live with day to day) are not even apples and oranges, more like apples and watermelons.