From a personal standpoint, this would make me afraid to try mods that I'm not sure are gonna be good.
I often like to download mods just to give them a try. A lot of the time they're bad, so I delete them. But in such a situation, I've still given the author a unique download for their mod, even though I don't think they 'deserve' any DP that my unique download will have contributed towards. And there's no way for me to say "Hang on, don't give this author something I don't think they deserve." Not that such a feature would help much.
But if the mod is great, I want to endorse, and comment about how much of a diamond in the rough it is! And I won't be able to do that if I never download it to check it out.
So it has the potential to reward people more than they deserve, or otherwise cut off a reward from people that do. The system would encourage "download-bait" descriptions because of this issue.
A somewhat more meta-problem would also be that this system could potentially eliminate competition from other sites that wish to foster a modding community. The Nexus is already considered to be one of the best sites for modding any game, and I'm sure rivals have struggled because of this. There was a kind of similar problem raised with Steam Workshop Paid Mods: It would drive people away from the Steam Workshop. This could have the opposite effect of making authors only want their work on the Nexus because that is the platform that will best reimburse them for their effort.
Now, obviously some rewards for the dedicated modders in the community is better than no rewards, especially since a significant amount of it is gonna be from your own coffers, but I think this concern of a potential monopoly is worth noting. If modders choose the Nexus for their mod to be hosted on purely for the monetary aspect, rather than the features of the Nexus that make mods accessible and help the modding community grow, then that might mean if some hypothetical competitor site that offers better features would not have people put their mods on it, even if that site would be a good place for them. In a probably more realistic argument, this system might also discourage modders from hosting their mods on their own site (such as what Enderal did), even if having their own site would be the best way to get the mod to work properly and deliver the information about it. The Nexus is already the standard place for modders to distribute their mods (as far as I'm aware), and this system might reinforce that even more strictly, to the point where the alternatives will struggle to flourish even if they offer things the Nexus doesn't, which might be detrimental to the modding community as a whole.
