There are mods that are highly sought after (primed etc)
There are strong mods that often appear in loadouts (streamline, intensify etc)
There are situational mods that are dependent on your build (corrupted mods, adaptation etc) goals.
There are average mods that are fairly standard use (redirection, stretch, vitality)
There are weak mods which rarely see use in regular play.
The weak mods either have very niche uses, or are there as a teaching mechanic both for how modding works, but also how mods interact with the game's mechanics and stats. And if you've already learnt modding, then it's an alternative source of endo. You can have content that caters towards the lesser used mods, but you can't have every mod in the game being equally valuable.
Mods in this game are mechanically similar to a collectible card game. As such, it's no surprise that there's a sizable chunk of mods (cards) that aren't very useful.