I don't know a single thing about a JD Hydra-flex, nor do I recall saying it is old technology. Neither do I own a MacDon. Sure did like the way it cut and fed field peas though.

As to why CNH is making flex heads: I suspect it is because they think they can sell some and return a profit for their shareholders. Probably the same reason JD makes both track and wheel tractors and both rotary and conventional combines. Same reason that Cat makes tracked and wheel loaders, track and wheel tractors. Claas makes track and wheeled combines. CNH makes track and wheel farm tractors.

If you ever managed to get one of the guys at corporate to tell you the flat out truth, I'd bet they would tell you that it matters not to them whether their product is the best for the job at hand. The object of the exercise for them is to sell the most and make the most $$$$