Hidden Power was an objectively poorly designed move in almost every way. It makes no sense for Pokemon to *randomly* have possible access to one additional move-type for coverage. The move just didn't make any sense at all, neither in terms of gameplay nor thematically-speaking.
Hidden Power was a relic from an era where Gamefreak did not want Pokemon to become a "competitive" game like many others (similar to how Sakurai didn't want Smash Bros to be played competitively, only for fun, and so implemented tripping). Eventually, both Gamefreak and Sakurai dropped this notion, as their games were inherently competitive by nature, and trying to stop people from engaging with that was futile/counterintuitive.
This is one of the better design choices Gamefreak has made, which follows one of the better developments of their philosophy with Pokemon which is to make the transition into competitive more smooth and accessible.
The deliberateness of this decision is also apparent in the fact that many Pokemon that benefitted from Hidden Power just so happened to receive new coverage moves in SWSH when Hidden Power was removed - which is the best solution to the problem of these Pokemon lacking coverage.
