I'll take a stab at answering even though I am not one of the downvoters (I actually cannot see the downvotes so I'll take your word that they're there).

First, I struggle to see the relevant difference between "is pathetic" and "coming across as pathetic". I'll try to make an analogy: I think downvoting as it currently functions (at least for lemmy/piefed) is a summary judgement that says "this content is not worth my attention, nor is it worth everyone else's attention." I think your distinction tries to differentiate between those two things, i.e. "comes across as pathetic" implies "this is not worth my attention" while "is pathetic" implies "not worth anyone's attention", and the simple mechanism of downvoting is not nuanced enough for that distinction. I think the distaste for saying "asking about downvotes comes across as pathetic" stems from a disagreement about whether such questions are worth anyone's attention, not merely your own.

Second, I think there's an element of gamification to upvotes and downvotes that leads people to seek upvotes and avoid downvotes to the detriment of... what I'll call for lack of a better term "actual conversation". I think this is worse on platforms like Reddit where one's global post and comment karma is easily accessible. We humans have an ingrained preference for "numbers going up" games that Reddit takes advantage of to boost its interaction metrics (and therefore its ad sales). This gamification leads to suspicion among users about the true motives behind inquiries about downvotes. If maximizing upvotes is the game we're all playing, then demanding a clarification for downvotes might be taken as a cynical attempt to save points rather than actually engaging with a controversial idea, and I think that behavior is broadly agreed to be pathetic. But that cynical pointsmaxxing behavior often looks a lot like someone who is trying to engage with a controversial idea, indeed I think the whole concept of "concern trolling" relies on exploiting that ambiguity. I think the automatic assignment of any questioning of downvotes to "pathetic" (either seeming or in fact) excludes the possibility that the asker is making a good-faith attempt to learn why their post was received so negatively by the community.