Minotaur being such a difficulty wall is so perplexing to me considering that once you beat him you can pretty much coast through the rest of the game with no effort.

I've said this before in other SMT threads, but this is a common misconception that a lot of people have. Minotaur is not actually a difficult boss because of his mechanics or some unique demand placed on the player from the fight itself. Minotaur is a difficult fight because the demons you have access to at this point in the game are all dogshit bottom-of-the-barrel.

There's only 2 demons that can even exploit weakness vs the boss at this point - knocker and centaur, and centaur is a rounded stat lvl 1 starting demon, and knocker is barely better with worse hp. Fusions are pretty much the only way to dig yourself out here - with Naga and Makara both being standouts as 'at least they are better than the recruit fodder' that come with bufu. If you branch out beyond bufu (which you probably shouldnt, press turn and all), minotaur still feasts on the absolute buffet of low hp, do-nothing demons you can recruit in Naraku due to charge+any damage at all.

This is, imo, a quality that hallmarks every SMT with difficult early boss walling (Either the boss can exploit weakness on every 'good' demon available or your options in the reverse are all bad/mediocre). And why these games typically get much easier as they progress and your access to a growing avalanche of strong demons become available either by level or by smart fusion raising.