1- There are not a lot of places that are geologically suitable for such schemes - Iceland has a geothermal district heating scheme but they are based right over the mid-atlantic ridge so geological conditions are pretty ideal.
2- We have not been very successful with the technology as it is not as easy as it seems. You need to pump water down into a hot source-rock, then pump it back up again in sufficient volumes to capture the energy, then you need to convert the energy into something usefull like electricity. This is really not very easy to do.

Geothermal energy has a lot of potential if we can crack the technology, just as wave power and tidal power have but it is not suitable for everywhere, just as tidal power would be pretty inappropriate for a place 100 miles from the sea.