Hmm…you just might be onto something…
Look at one of the modern darlings of coop shooters: Deep Rock Galactic.
I never gelled with it, so I’m not 100% current on my knowledge.
But I believe it has half or less the amount of modifiers that DT has in its stable.
Yet no one is complaining about mission variety there.
Sure, the proc-gen maps help, but I seriously doubt it’s carrying all the weight of variety in gameplay since they aren’t that different.