In his previous post, Jeff said that better art styles would increase his sales. So he doesn't feel that this would be gambling his future.
I don't think people get that making something a little less sucky doesn't really result in appreciable sales. Even if he improves the graphics a little, it's still going to be a dated text-heavy PC RPG that is based on a certain time. Like, if you don't enjoy retro styling, the difference between a game like The End is Nigh and Iconcolasts isn't really going to draw you in, nor would End's simpler graphics be an issue. Maybe a huge stylistic increase like Hollow Knight might though.
Coherent art would cost him more than 3 times his current art budget.