Jerry,
Got to call BS on you...
If you accept that Harley, for marketing and reasons of tradition (pretty much the same thing) must stay with air-cooled twins. Then you can blame the EPA. Two valve, pushrod, large displacements V-twins have to run hot if set up lean enough to meet EPA regs. ALL you examples are water-cooled.
I gave you a couple examples of water cooled automobiles which meet much tougher standards than what Harley has to meet. If you like, you can find plenty of examples of air cooled engines that meet the same standards as Harley but they do it without all the crappy driveability and performance problems Harley makes standard. They also do it without selling you illegal tampering devices and parts to "fix" the problems they purposely pawn off. Go by a BMW dealer and ride one of their air cooled bikes, or Honda, or Yamaha, or Victory, or whoever else out there that I can't remember at the moment.
The EPA has cut a ton of slack for H-D for decades, but eventually everyone has to comply with the law. When only one company seems to have insurmountable issues, that tells me it isn't the regulation, it's that company.
BTW, as Red Devil mentioned in his post, and as I've mentioned in several other threads, Harley isn't the only engine out there that runs hot. All internal combustion engines produce heat in large quantities, and much of that heat is waste heat. Water cooled engines also run hot, and if anyone doesn't believe that I suggest they take their car out on the highway for about 30 miles at speed, then pull off the road, pop the hood, and sit on top of the engine. Try not to burn your butt off.
The heat issue is a two parter, and some folks around here seem to get the two parts mixed up. One is the reliability issue, where running excessively high combustion chamber temps affects the parts negatively (when the materials and designs aren't up to the task). The other is rider comfort, which is more of a proximity and shielding issue. Face it, the bigger the engines get the more heat they produce and the more they radiate that heat onto nearby objects like your legs. That is true if the engine meets EPA standards or not. Hot is hot, and the difference between 1000 degree pipes and 1400 degree pipes isn't the main problem. Both will burn the snot out of you, and wise folks will avoid both. The folks at H-D could have helped isolate the riders from much of the extra heat with better designs and shielding, but those things cost money and might mess with Willy G.'s idea of style. I'd like to know how you blame that on the EPA.
If someone really wants cooler, they could dig up an old Pan or Shovel and restore it. They didn't make enough power to generate much heat, so the obsession with heat should be satisfied. They also ran really rich and dirty, and leaked oil like a sieve, and weren't terribly reliable, but by god they ran "cooler".
Jerry