Earlier quoted context omitted.
I could never understand why some people don't understand that people buy into a community because they like the community in the state when they bought into it. And that making large changes to the community would alter the community and what people liked about it will be diminished. Not to mention the practical aspects like utilities, road capacity, schools, etc. as you've pointed out. For some reason, some people…
I'm probably one of those people you're referring to, and quite honestly it's not that I don't realize or understand - it's that I don't care. The community you love wasn't always that way - it changed to become what you enjoy, likely to the similar anger/detriment of the previous residents who like the "old" community. I imagine racial segregationists and apartheid advocates used disconcertingly similar arguments.
There are plenty of already-urban areas that have poorly-used lots that could benefit from building more urban housing. Why not start there? Keep like housing styles together: If you're the one single family house in the middle of a city surrounded by dozens of apartments, then yea, that lot should probably be re-developed into an apartment. The single family home is out of place and the neighborhood is already set up for dense living.
But if you're in a small town that's all single family houses, it doesn't make sense to re-develop a random sampling of them into apartment buildings. 1. They'd look out of place and 2. These small towns don't have the infrastructure to suddenly 3X-10X their populations. They'd need more schools, transportation, electric capacity, water/sewer capacity, trash collection, retail, industry, everything.