If the result is that presidents in the future think twice before holding up military aid in order to gain leverage for their own re-election, I think we can call this a net win in terms of precedence.
Your point regarding setting a legal precedent for presidential privilege is interesting, but perhaps "true Republicans" would thank the Democrats for not pursuing it right now: given the now-politicized Supreme Court, there's a good chance that the result would be a strong blow to anyone that was hoping there were still checks and balances against an ever-more powerful federal executive branch. However, I believe the Democrats in the House probably chose not to force the issue more on the basis that the electorate these days seems to have too short an attention span to wait for an actual legal battle to reach a conclusion. It looks like they blew it with not holding out for more witnesses, but I can see how it was a hard call.
As for the rest of your arguments, there is literally nothing of substance in the second paragraph, so I think I we can just leave it with imagining you "trying to keep a straight face" while writing it.