I must say I disagree with this. I don't know if it's because of differing opinion, experience or game engine/language, but with Unity navigation it's quite easy.
You mean with the enemy path finding? Yeah it can be easy but I think part of the challenge is making it look like the enemies aren't just following A* algorithm paths or whatever, plus custom behavior. I will say it is much easier to design any genre today than it was 10 years ago, that's for sure.