But the most entertaining part of the game is trying to figure out your surroundings through sound. Why add visuals and disrupt the illusion?
Viewing post in Ptolem's Singing Catacombs comments
I believe this game was honestly more of an experiment to see the challenges associated with making audio games. I see your point about the visuals but if you want an option to turn on visuals in the menu then surely you would peek anyway. If you want an option to turn on visuals but can't trust yourself if you just turn off the monitor then GMT's point is not relevant. here is a link to a devlog the creator has made which you may find interesting:
In all seriousness now, I think the point of having visual elements is to make it acessible for not blind people too. Look it this way: If you have a blind friend, you could share this game with him and both YOU and HIM could experience the same game.
So you have a game in common you could talk about with said friend(even tho you both experienced them in diferent way). Imo that is pretty cool.