I think a good deal of the angst between hiker and biker factions could be eliminated by bikers simply following the "guidelines" of yielding to hikers. Problem is, I don't know how practical (or doable) bikes yielding to hikers is in the real world.
I hike and run on very heavily shared MTB trails and the majority of bikers I encounter will rarely yield to those on foot.
Now personally, I don't care in most cases, and think we can co-exist just fine if BOTH sides give a little courtesy based on the situation. Seeing someone coming through a section, if I can easily step aside and let them pass, why not? It doesn't make a lot of practical sense to require the faster moving person to yield to the slower one. I used to MTB a lot and always appreciated a hiker waving me on.
Problem is, did they do it out of politeness or out of fear of getting run over? There's a big difference, and I don't think it's always very obvious to a rider.
There are many times I have to yielded to bikes not at all because I'm being polite, but because with the speed, width of handlebars, and width of trail, it's not practical. Expecting a biker to yield on a steeper downhill section, especially if it's rocky, doesn't work; so again, it's not exactly because I'm being cool, it's because if I don't get out of the way, someone's going to get hit or fall. So basically, it's a biker forcing me off the trail. I think anyone forcing anyone off a trail is a bit rude (don't get me started on mule trails and horses).
And I must say, it can get pretty annoying to be left in a trail of dust because a string of bikes blows past me, especially when you step aside for the first rider and they simply yell "Three more behind me!" then are left standing in the bushes to get blown past by the rest.
Hikers and runners can typically pass each other, even on singletrack, without anyone feeling like they've got to get into the bushes or off the trail to give room.
The scenarios I mention are pretty regular where I live, I'm not going for argumentative hyperbole here. Ask anyone that rides in the Angeles National Forest about the popular El Prieto singletrack; a beautiful little front range section right above my house. I used to ride it a lot. But from a runner's or hiker's perspective it can be pretty scary because of fast downhill MTB traffic; they take the fire roads up and bomb the singletrack down. I certainly wouldn't want to hike it with my family, especially not on a Saturday or Sunday morning, no exaggeration. So is that fair? This sort of thing does get under people's skin.
I don't think it has to be an either/or situation, but I do think there are some serious etiquette issues, especially concerning speed and right of way. In the end, I don't know how this sort of stuff gets solved; it's partially like trying to legislate that people not be rude to each other.