They are routinely used by the business jet community.
The prices start at about 30-40 euros, for a validated Eurocontrol route and a weather briefing.
Higher up the food chain, firms like Jeppesen make $millions by selling flight support services starting at a few hundred whatsits per month. I guess they also do overflight permits (necessary in the 3rd world, generally) and hotel bookings for that...
Light GA is usually tight with money and rarely uses these services, especially now that the major "black art" portion (the development of valid Eurocontrol IFR routes) has been made available to normal mortals, using software tools like FlightPlanPro. Any monkey can book hotels, etc, over the internet.