Do you live in Wong Chuk Hang? Your description of your home sounds like mine. My building is sandwiched between the water & a mountain (with water/mountain view looking out towards jumbo) - no potential for new buildings
I do agree with you regarding quality of life (noise/light pollution) but I think whether the macro QoL decreases has much to do with how policies are implemented ie: where will the new structures be built, in what manner, and will they be built in a rationale fashion.
The way that I see it, it is definitely true that creating more flats does not mean that housing prices will go down. For example, HK adds more flats but net immigration changes (for whatever reason) = possibly more people needing housings that new flats being available. So I don't think adding flats is necessarily going to work.
However, if HK does not add new flats, housing prices are very unlikely to fall (I won't say impossible, another SARs incident could occur). So I think that HK should add new flats because there's the possibility that housing pressures will ease. But they need to do so in a proper and non-dumb way.