Fail gold on national wonders always caused me the most anguish since there was no way I could convince myself that the designers would have thought this was legit. I can always be blind to it on world wonders since it was a consolation but not on national ones.
Agreed, and if they did only convert 50% it should be unmodified (in terms of like marble or stone bonuses) I don't mind the hammer bonus from them but to get fail gold based on that just seems way to cheesy.
Yeah, that along with Wealth and Research being so efficient are imo the biggest flaws with this game, as it means optimal play requires you to forgo most buildings. Personally I think Wealth and Research (and Culture but that's less relevant) should only convert 50% of Production, and you should only receive half of the hammers in a wonder into failgold. Research, Wealth and Failgold should imo be emergency measures, not the backbone of your economy.
I think trying to get the best result in single player games is all about finding the games boundaries and exploiting them. From that guy making reaching the maximum population physically possible in SimCity 3000 to a guy making a 13 minute morrowind speedrun, it's all about pushing games to their limits. So I think that's what interesting to most deity players, that they really understand how the game works internally.