The ultralight cult is interesting, and while it is true that some carry it to extremes, there is a lot of value for less rabid practitioners. Packs are lighter, with less padding, etc., primarily because they are carrying less. It is a feedback loop - the lighter your load, the fewer features you need in your backpack to pad and protect.

I have one such pack and it is fine for purely recreational, non-technical excursions. I have others which I carry when the job requires additional, usually relatively heavy, items.

The idea of a bedroll vs a backpack is interesting, but I wonder how the bedroll would work when scrambling in steep, rocky terrain and in dense brush, compared to a well loaded back pack...