The point of accessibility is to allow proportion of humanity to
live normally, to do the same things that most of the rest can do; i.e. work, see a movie, and yes, take in a view. The reason to do that is that it improves the lives of the smaller proportion while at least not injuring the rest. (You believe only having stairs in a tall building would be a
feature?)
Are you willing to make the argument that looking out from the top of Everest or tramming to the bottom of the canyon for an afternoon is something that everyone should be able to do? That it's more important than preserving those areas for the future?
A while back, I had the opportunity to visit Blarney Castle in Ireland. As it turns out, the castle is an unreconstructed ruin; if you want to kiss the stone or at least take in the view, you have to climb a long, cramped, tight, steep spiral staircase. I'm old, out of shape, arthritic, and not fond of being the cause of a fairly large scale body recovery in the middle of a major tourist attraction, so I didn't go up. So far, I haven't noticed any consequences of the lack, and from what I enjoyed about the site, I'd just as soon they didn't strap an elevator to the side of the tower.
Everest tourism has costs, both in terms of sheer litter and in the lives of people who probably shouldn't be doing it anyway. Grand Canyon development also has costs which would reduce the value of the site. Are those costs worth the benefits?