It’s elevation change not justified by the terrain which is an issue – doubtless if they built such “infrastructure” in the fens there would still be elevation change. It’s just something which makes it feel like an afterthought – if it was all considered together then the designers should realise that elevation change is far more of an issue for bikes than it is for cars, and the roads would change elevation to cross the bike paths.
I admit I was on something less suitable for any purpose than a normal bike, but I have a lot more issue with hills hence why I wanted something as flat as possible (the terrain was fine, it was the slopes added by the designers which were the problem).
As mentioned on the other thread, bumps are also a big issue for me – no reason why bike paths can’t be free from those apart from political will to build them properly.