2:21 p.m. on April 12, 2011 (EDT)
you have made some good observations; for me, it depends on how the hook/loop is used.
applications where it works:
-closure tab over the top end of the zipper on my sleeping bags, and to link the draft collar. never had a problem.
-hard shell cuffs - can fuzz up the shell material a little, but it's nice to have an easy & secure way to adjust the cuff.
-hard shell rain flaps - used sparingly, it's OK, jackets and pants. better than snaps, for me. on hard shells, the hook/loop isn't usually exposed to enough debris to render it ineffective. at the bottom cuff of rain pants, though, snaps are better due to the risk of mud clogging the hook/loop.
-backpack torso adjustment: some brands adjust torso length using hook/loop to allow the shoulder harness to move up and down, then re-secure it. Mystery Ranch and Osprey come to mind. generally, that means a one-time adjustment so the pack fits you, then leave it alone. because the hook/loop is behind the back pad, protected from debris and from your clothes, it doesn't tend to snag anything and doesn't lose effectiveness. for this purpose, i like it a lot, so long as it's sufficiently wide to secure the shoulder harness.
-gaiters - i'm a little on the fence here, because gaiters get dirty and muddy. but, the convenience of being able to easily take them on/off with a hook/loop front closure is too tempting. besides, they don't seem to get sufficiently mucked up to prevent the hook/loop from working. i have a pair of low REI gaiters that are at least ten years old - the ones i use when i expect really muddy trails - and the wide hook/loop strip along the front remains bombproof after tons of use. advantage - you can hose them off and throw them in the washer, which does a great job keeping the hook/loop debris-free.
-not good - water shoes. too much risk of fouling up the hook/loop closure with sand or mud, and there are better options. chacos, where they tighten via a slider clip engaging the webbing; or Keens, that usually rely on an elastic or a slider clip.
-tents - i have used tents that secure the rain fly to the poles, in places, with hook/loop. it's a pain to fasten/unfasten reaching under the fly. plastic clips would be a better choice for me.
-outer parts of the backpack - i agree that if a backpack has a hipbelt that adjusts somehow using hook/loop, it creates a risk of annoying clothing snags if the pack isn't well-designed.