The problem with pumped storage is most of the places we can use it are already taken and have been for years.
> pumped storage is still significantly cheaper for seasonal storage
Only because most of the costs have been financially depreciated long ago. Try to build a brand new dam nearly anyplace and the costs will be much higher.
> we can use it are already taken
There are literally millions of unused locations identified that are suitable for pumped storage: https://re100.eng.anu.edu.au/global/
hydro generation sites are mostly taken. pumped storage doesn't need flow, just 2 reservoirs (one or both of which can be built) and a elevation change.
> a brand new dam
pumped storage facilities generally don't use dams.
You have to have something to keep the water contained between the two.
But those aren't dams. Dams are something that stops the flow of water. And it's this stoppage that causes the environmental problems.
Reservoir walls might look like dams, but they're not dams.
Pedantically you are correct. However you are completely missing the point.