I agree that a "donate" button should always be allowed.
However, I think being allowed (both through media like the Steam Workshop and renowned sites like Nexus) to actually charge for mods will quickly encourage a very unhealthy and ultimately deserted mod community.
I wouldn't look at it that way. First the basic mods one gets, stats, items, gfx, people simply wouldn't buy them, the market would handle that, precedent has been set.
However if we want real quality full campaigns, imo it would encourage quality devs to invest the time. Every purchase I make is always measured, if it is an outstanding mod or a standalone, if the $/quality ration is there, mod or not to me no matter.
As for what happened in the past... there used to be a very small indy scene, no kickstarter, no greenlight, no early access. The canvas has changed, perhaps a few dollars to real quality efforts is the next area to explore.
