That seems very silly. About it not showing benefits yet: are you talking just about the Skyrim incarnation here? Because I'm sure the people making their living on DOTA items might disagree. And for Skyrim, it has hardly had the time to show any benefits as I'm sure you can see.
As for the Nexus somehow being more ethical: sorry, I don't see it.
Absolutely - some people just seem to like screaming about the sky falling.
It is a problem of player expectation versus reality. And a problem of fear-mongering and concern trolling.
If people see no value in a given mod they won't pay, and after a short period of normalization nothing will change for modding. If people see significant value, then the modders creating that value will have more incentive and opportunity to create even better content.
Fun fact: in my experience, less than 0.17% of all mod users donate. If you actually want to make a living or even just support yourself with modding (which I think is a bad idea, but I wouldn't want to stop anyone from trying!) then donations are entirely unsuitable.
And I guess I should repeat myself since people have taken my position out of context or even entirely misrepresented it over the past dozen pages or so -- in answer to: "Will you end up charging for DSfix someday if it became available through the workshop?"
There is a way to make a living off modding: apply for a dev job.