I have had poor experiences with Reddit advertising as well, although with similarly small sample sets.

My ad ran site-wide for 2 days last December (total $40) and saw 331,901 impressions but only 148 clicks (CTR of 0.044%). Since it was advertising a free app which itself makes money through advertising, each of those clicks (and the far fewer conversions) were worth a lot less than what I paid for them.

I bet Reddit advertising works great for expensive physical goods (like watches, Amazon affiliate links, and Not Safe for Wallet links I see advertised a lot) where you can afford to spend a few dollars per conversion in advertising, but it does not seem to be a very good choice for apps.

The horrendous interface is likely a symptom of the poor quality of the codebase he developed for Dwarf Fortress.

Look at his other projects, such as Liberal Crime Squad (http://www.bay12games.com/lcs/). The code for LCS available on that site is atrocious. I know, because I helped to convert the 38K lines (yes 38 THOUSAND LINES) of code in a SINGLE C++ FILE into something that is actually maintainable when he open sourced the game (fun fact: the IDE I used back then would crash when opening that file).

The reason for this is clear, like you say, Tarn comes from a physics/math background. He does not seem to be very experienced at software engineering (at least he wasn't 9 years ago when LCS was open-sourced). I would not be surprised if the Dwarf Fortress codebase is just as inscrutable as the resulting game.