Why is Kuva valuable?

I dont farm kuva. I dont even run kuva missions. I dont enjoy them. Dont really enjoy the kuva fortress tileset either. I do a lot to avoid kuva related missions, but I still have heaps of it, that I dont have any use for. I've cycled a handful of rivens, but most of my rivens just get squashed into endo.

Why is Kuva valuable so valuable to some? Is it a PvP oriented resource? Is it really useful if you're into some aspect of the game I haven't seen yet? You can't even heap it into big wiggly gold stacks on the deck of your ship like you can with socketed ayotan sculptures. :D

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Edit: Aight, I'm getting it now. Looks like people sometimes find rivens for guns that are community beloved, and then they either roll them repeatedly until they are perfect and sell them, or they sell them to someone who rolls them repeatedly. So while all players dont need to gather heaps of kuva, a handful of players will want access to MEGAheaps of kuva, to affect a specific Riven.

I'd imagine the same rivens float about eternally, as well. Some weapons will eternally carry high favor among the community, but the precise riven effect may subtley change over time, leading to multiple parties reselling and rerolling the same rivens endlessly.

I'd be curious to hear from developers, who hold the rivens that are the oldest and most rerolled, of all time.