Maybe it's because the American government won't allow spares to be supplied for American helicopters operating in countries which they don't approve of
With Bell mixed in, the A139 had a much more limited market, but now, like the French,they'll doubtless allow their helicopters to get spares back-up (well, if you can call Eurocopter's a back-up
) and be able to sell a lot more to countries whether America approves or not.