I mean… You live in a world where magic healing exists. Why would anyone be blind when you can find a sorcerer, wizard or cleric (or even a spoony bard like Volo) and restore your sight in at least 20 different ways? 🤔
This was a bit of weird shit in Star Trek with Geordi, too. They can literally grow him new eyes (and do eventually) but the visor is also cool, and the rule of cool wins.
It’s not so much that a disabled person being realistic is unfun; it’s that it doesn’t seem to fit the world itself which kills suspension of disbelief if you understand how the game world works. You’d have to work extra hard at giving a believable reason for this person to be disabled and not have gotten healed through magical means.