Hydro is great, except for a few problems. The biggest is that they are causing extinction for several species. The second biggest in central and northern Europe is that hydro is already used in every place where its reasonable to build them, with practically no space to further expansion.

Right before the last rush to build nuclear, Europe went through an energy crisis where they did also use reverse hydro. In recent time there has been discussion to modernize and reuse those old installations, but the issue is costs. Buying energy to sell it later, while maintaining and operating the hydro power plants and pumps are not cheap (not to mention building out transmission). Even at current fossil fuel prices, natural gas and oil is cheaper and thus reverse hydro is not economical viable.