Cost is the main reason why light turboprops are not more common. You can buy a turbine conversion for your 206, 210 or Bonanza - starting around half a million dollars. An uncertified engine is available for quite a bit less if you are flying experimental but this is not an option for Europe-based aircraft.
You also need a higher level of technical expertise to maintain one on a homebuilt.
Jet fuel is taxed, for private use, in Euroland so the running cost benefit no longer exists.
Pilot training is also an issue - type ratings etc for turbine power on the eastern side of the Atlantic. Probably quite awkward to define in an uncertified model.
Change, in aviation, is very expensive (because the authorities say so) so don't expect any in the near future.