re: Please tell me why we should NOT see Trump’s tax returns.

Because you're trying to hypothesize a crime or other foul up front, and only then go in search of something to support your hypothesis. Plainly stated...that's just not how it's supposed to work. Reverse engineering a scandal.

This seems apparent...Dems want everything under the sun on Trump so they can find anything to hit him with. Now, if some specific allegation comes up that makes his tax returns relevant...that may be a different ball of wax.