Humbe Bundle has been focusing on profit only and ignoring their original values ever since it has been sold to IGN. It's not surprising that they would cut support for something only a small percentage of their users use (remember, they are primarily a Steam key reseller now). That has nothing to do with Linux support being cumbersome just with any OS support benefiting from economies of scale that makes minority platforms less lucrative.
When they were publishing pie charts and made you fill a little questionnaire every time you buy a bundle, the stats showed that Linux users always paid a little more than the average, and this exponentially added up causing Linux users to pay a much greater sum at the end of the bundle, in terms of total money spent.
I'm not sure I can find the charts now (they were live and per bundle), but I track Humble since day 1. I remember it well.
Some of the earlier Humble Bundles had Linux users contributing about ¼ of the funds but I don't think it was ever higher than that. [0] These early bundles were also before Steam for Linux was a thing so were a major source of new Linux ports (relative to the number of available native games).
