The overwhelming majority of the people complaining about this are well-paid tech workers writing code for well-funded companies that profit off of open source code without providing any reciprocal value to the open source projects in return. (Of course, that statement isn't true for 100% of companies, but I'd guess that less than 10% of companies using open source code donate back to the open source projects they use)
Something about this whole debate makes me a bit uneasy.
You have people working mostly for free, developing open-source, FREE code that provides incredible value to the for-profit companies that use the open source code to generate (sometimes) massive amounts of revenue.
Given the amount of value open source provides to for-profit companies (with the open source maintainers rarely getting any reciprocal value from the companies that profit off them), why is it so alarming to think that these maintainers might think of a clever idea like this to make a couple thousand bucks?
I'm not arguing that npm install logs should be packed full of ads (it shouldn't).
But instead of attacking the guy for trying, I really wish the discussion were focussed on how the community of open-source consumers can contribute back to the open source ecosystem in a way that promotes the sustainability of the projects and community.