I think that camping equipment is sort of converging in design between brands due to technology, to some extent. I have an old Kelty aluminum external frame with a Boyscout catalog camper packbag. I tore up two hip belts before I figured out how to properly mount them. (This is when I was like 11) I hiked many miles with it. To be honest, with my normal load it is perfectly fine for me. With a good proper hip belt it can be far more comfortable than the old military packs with simple belts and sparse padding. More modern military ALICE packs are pretty good, but a bit short for real freight packing in my opinion. Good thing I don't have to use one.
Of course, I am also not afraid of packing a distance with a canvas softsided rucksack as well. I tailor my loads to my pack and the conditions, and just live with having to shift the weight around to get comfortable.
Nobody seems to be offering external frames because they aren't cool any more. Simple as that. If camping equipment hinged on sheer practicality there wouldn't be so much junk in sporting goods stores. Some people prefer more modern designs, but that doesn't mean the old designs are useless. If you really wanted an external frame pack, Campmor has a free catalog with gajillions of packs and bags in it. If anybody had an external frame pack they would, I think.