Okay, to make it short, if we could make the mods we do at Ace, and incorporate them into the OEM production process with over 100k numbers of production, we could get it done at a very reasonable price. The reason we can't do it in the very small numbers we work with is "economy of scale in production". We do "one-sies and two-sies", which is always the most expensive way to do things.
From what I'm reading about the Continental, they wanted to use as much of the regular engine parts as possible, to keep production streamlined and commonality between models, resulting in minimal cost increases for the engine.
They already had quite a difference with the rolling chassis( in cost and other features), so they probably didn't have much more room to add cost after all of that, and still achieve their projected price point.
Certainly, more power could have been extracted from this UCE powerplant, but it's clear that the factory made the decision to not do it. I don't know the reasoning behind it, but again, I suspect it is cost.
I'm not going to address an imagined comparison between a 10,000 rpm crotch rocket and a 5000 rpm thumper. There simply is no comparison there.