In the very long term, yes a large plot of land in a densely-constructed city would be extremely valuable. In the short and medium-term though, the downward price pressure of increased supply outweighs the upward price pressure of amenity effects.[1][2][3]

Very few NIMBYs will openly admit to wanting to maintain their property values because it's a much less noble sounding cause than "preserving the character of the neighborhood" or whatever.

1. https://research.upjohn.org/cgi/viewcontent.cgi?article=1334...

2. https://blocksandlots.com/wp-content/uploads/2020/02/Do-New-...

3. https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3867764