My main gripe with #music streaming services that offer "similar songs" features is that once a song is featured in an Original Soundtrack, it just becomes "movie music" or "video game music", regardless of its actual musical quality. So you can't ever find songs that are of a similar genre because "movie music" or "video game music" doesn't tell you anything about how it sounds.
@hypolite A similar problem occurs on TV/movie sites with the genre of "anime" :-(