I believe modders definitively are worth more than users since they are the website's content aggregators and are responsible for bringing an influx of users to it. There is no denial in that. But it doesn't excuse them to be toxic toward their userbase. While good manners are expected of user, a tighter and more mature attitude from authors should also be expected on the Nexus otherwise we end up with ban-happy like those. As a modder myself, it abhorres me when I see people who think they are superior or better than others and demand satisfaction by deleting negative constructive cricitism.
While I believe banning people from downloading your mod is incredibly childish, what stops the banned from logging out, downloading it and logging back in (unless its an IP-based ban)? Having this in place only encourages ban-happy modders and toxic attitudes within the community. Sometimes one should indeed block a person who's been pestering and never fully content with a mod that's not to their liking, but this should be a last resort. That user should download the mod the way it is or not download at all.