Oh and the US manufacturers aren't? They get more than enough investment through their government programmes but haven't invested the profits in R and D,relying instead in spinning off technology from the military research programmes.
The situation surrounding the pace of commercial rotorcraft technology development is different than that of other types of commercial aircraft. It takes huge amounts of time and money to bring any new commercial helicopter model to market, even more so if the model involves lots of new technologies. The total global annual market for new commercial rotorcraft is not that large, in terms of numbers or value, compared to the market for commercial/business fixed-wing aircraft. Thus it is very hard for management of a publicly-held company like Sikorsky or Bell to justify committing hundreds of millions of shareholder dollars on a completely new model, for a period of up to 6 or 8 years until it produces some positive cash flow and profit.
This is not to say that there is no new technology in the commercial rotorcraft market. It's just that the types of new technologies are those that can be integrated into existing models. Things like better blades, better avionics, active vibration control systems, FBW controls and software, etc.
A perfect example of how difficult it can be to bring an advanced commercial rotorcraft model to market is that of Bell with the 609 tiltrotor. I would also point out that Sikorsky/UTC is spending its own money to develop the S-97 model.