The conflict between Taiwan and the PRC is largely based around culture and politics.
First, culture. The PRC is an Imperial power. For, oh, the last 2000 years this same crap has been going on.
Meaning, the Chinese have been going on and on about only having one Dynasty at a time.
Taiwan represents the last ideological holdout-preventing a dynastic consolidation of power under their regime.
Communism is a side issue. Its foreign to China and slowly dying out. Dynastic rule on the other hand is not, and its as strong as ever, and in fact, being revived. Thats the crux of the issue.
Now, is having a unified 'China' (A word that doesn't even exist in Chinese) nessesarily a bad thing?
No. BUT, it depends on how that unification happens. If its done via some brand of facism (again-not at all foreign to China) and for no other reason other than facist politics...and not to mention killing people over it...should we allow that?
Picture this: Saddam having some poor Kuwaiti kneeling at his feet---and forcing him to confess that Saddam is the King.
Truth is, he tried to do that through nothing more than mideval means-- and China is no different.
To just turn a blind eye is literally to deny everything we stand for in the world. After WWII what was set up in Europe? What about Japan? Truth is, if we let it run wild in Asia...it will.
The only route out of this whole affair is for the PRC to change. We will either have to engage them now, and prod them along to change in a civil manner...or we will have to conquer them later and change them by force later.
"Communism is a side issue."
I agree with most everything you said, but strongly disagree with the above statement.