I consider the question of how far language should adapt for transgender people to be a reasonable one. Transgender proportion of population is on the same order as blindness. Many would consider it excessive to remove all non-eyesight uses of "vision", analogies like "I see what you mean", etc from our discourse.

It's absolutely fine that you disagree with JK Rowling. It's also fine that she disagrees with you. Talk about it! Don't throw slurs at each other. Don't make personal attacks.