I strongly disagree with your statement! Also if you ask me a statement like that just shows your ignorance to any form of travel weather it be train hopping, hitching, flying, Amtrak, buses, hiking, or just spending real time in the wilderness
Almost all packs have a time to shine... Example when I go on long hikes with my 12lbs of gear, a pack that light does not need a frame of any kind, internal or external... So that pretty much blows your statement "framed packs are superiour to any non framed pack" out of the fucking water!
External frame packs are good for humping a LOT of gear a long ways but they suck for riding trains or hitching... Good luck getting your external frame 5000 cubic inch pack with all that shit hanging on it into a hole of a CP grainer, or maybe into someones tiny car that is packed with crap when your hitching....etc.
Internal frame packs are good for most people doing most thing, and packing standard amount of stuff 20-30lbs... Hitching, trains, hiking...etc. That's why the majority of packs are this.
Ultra light weight packs are good for just that... If everything you carry is under 15lbs you really have no need for a frame support in a pack.
There is a reason you don't see people hiking with ALICE or MOLLE military packs... Its cause they suck and they are heavy as shit... They are made bomb proof for going to war... and often times they are very over built for riding trains, hitching, hiking...etc.
If you look at the 'traveler' community and I use that term loosely here and you look at the type of packs different people use you will likely see the same trend I see...
People that are all fucking 'HardCORE!' dirty kids like to portray the look that they got going for them and have that beat to hell ALICE pack, these people will often live and die by that pack since its part of there image and having a well fitting quality pack would likely get them made fun off by there shitty friends... Your average lower-middle class rider that is not all Mr. Crusty Punk that may have started riding trains with a $15 ALICE pack will likely upgrade to something better when they have the means to since they are not fun packs to own and use.