The peak force in the front of the knee happens at about 100-120 degrees of flexion. Think about going up stairs or a hill, now think about going down. Way up is more like a below-parallel squat, way down is more like a partial squat. This is why the deep squat is a position of relaxation for about 3 billion Asians and Africans, and the partial squat is a position of punishment for soldiers.
There are a few articles about runner injuries that basically say, uphill is rough but not horrible, downhill is nasty as shit. That sudden stopping with your knee at 100-120 degrees of flexion is just a lot of force through the front of your knee without the benefit of your hamstrings etc to balance it out (as happens in a deep squat).
This does not mean never do this stuff. It just means most of us won't be able to do it hard for years and years. But that is true of everything.
I know nothing about hiking, but from what you describe, you may want to look at Altra shoes. They're minimalist, but have lots of cushioning (relatively speaking). I could describe them as a running shoe with an extra wide toe box and zero drop height. It sounds to me like they check every box for you.
I work for the Forest Service and my job is to literally hike up and down mountains all day, every day for a living. The cartilage in my knees has yet to turn to ground beef. This is also while lugging around about 50 lbs. of field gear, food, water, etc. Having strong legs and a heavy squat helps...a lot.
I started walking stairs at my work a few weeks ago. 2-3 days a week for about 15-20 minutes each session. There are 7 flights of stairs. I start off on the 6th floor and walk all the way down and then all the way to the 7th floor. On the way up I do 2 stairs at a time. On the way down I don't skip any stairs and I try and take my time going down with the goal to recover as much as I can on the smway down before I start my next cycle up.
How do people feel about this type of exercising? Anyone here have good luck with it with fat loss and building up conditioning?
I sometimes run the stairs in my office building. Up two floors, breathe, up two floors, breathe, etc. Then take the elevator down.