Is it always true? More than once I heard fears about undesirables moving in, crime rate growing, the neighborhood "losing its character" that commands the high prices, etc. The resistance is real at some places.
The land value argument is downstream of the real issues - some people don't want change and fight it.
If it was purely a money question you could just get some billionaire to go around buying out entire neighborhoods, redeveloping them, and turning around and selling them off for a profit (because they'd be worth more, right?) - the fact that this is not being done either means there's a great new startup or there are other issues.
