> Your complaint about apartments can just be straightforward, you can say that you are concerned with the possible nuisances that can come with dense housing, and you don't trust the current enforcement or rules to allow you to enjoy your property peacefully. That is a perfectly valid reason to oppose something.

Great, that's one of the things I wouldn't want. But I also don't want to live in a city, which is why I didn't move to one. The other aspects of city life (noise all the time higher crime rates, etc.) are what many suburbanites are referring to when they talk about the character of their suburban neighborhoods. It's not hard to grasp, and there's significant overlap in what individual people mean. That's why "character" is used as a shorthand.