I dunno, what level of high regard are you talking about? I don’t have an up-to-date list but I think it’s probably around my 160th-170th favourite? In any case, I thought the art style was rather interesting/unique and at least above average for when the game came out, the writing quite passable and the scenario and characters reasonably well designed. It’s also a bit of a different kind of story - I couldn’t really point you to anything like it, translated or untranslated.
I don’t see what’s wrong with that - in fact, I thought it was the best ending in the game (although partly due to weaknesses in the other route endings, like you said). Something that carries strong emotional weight is good storytelling whether it’s positive or negative.
The full-voice version rectified this a little, although many of the added scenes felt ‘omake-y’ at best - it still felt a little bit short for the number of routes (although it makes a bit of sense given the short timeframe the game takes place over).
Need to bully JAST into translating it as a free patch for Crescendo.
One thing to consider is that for a number of years around the time the translation was released ‘story-centric’ translated eroge were fairly few in number, and while it pales against a lot of the titles available now, it certainly looks quite good compared to most (all) of the nukige (sexromp) titles translated.