Whether MIDI packs are worth the quality and diversity is a personal decision.
Some people find it beneficial to have a personally curated folder of VSTs that they use for their own music and other projects, whereas others may need commercial "pre-knows" (because they know very little about how to make their own music) or not want needless assets cluttering up their hard drive. It's really up to your personal tastes and needs as far as what you feel you need/want in your set-up!
But there's no denying that MIDI packs contain all the Leads, Chords Baselines, And Melodies necessary for music production. Free versions won’t offer you that much diversity when it comes to genres.