As odd as it is, to a sincere player, this eroge plays out very much like a normal eroge. In fact, I would go so far as to say that by allowing the player to empathize with disabled individuals, it might serve to improve treatment of disabled individuals.
Granted, I’m not the best person to make a call on normality, given that my 100% suspension of disbelief even extends into real life, but I don’t even notice the disabilities while playing. They’re an occasional source of concern, yes, but it’s not very much different than any other sort of concern. It still feels very natural.
But why take my word for it? Read some Kotaku.
I have mixed feelings about Katawa Shoujo, but I heartily disagree with your sentiments about this eroge.