longri wrote:What exactly is the downside of using a hipbelt?
To properly answer that question, it's necessary to first step-back and take a look from a macro perspective of where technology is going and why. To wit, the basic governing idea is to increase the respective strength/warmth/flexibility to weight ratio. This is true in all sports, commercial activities and manufacturing processes. Consider the impact of carbon fiber on bicycles, (race) cars, airplanes, etc.
The biggest advances in surfing have come from lighter, stronger surf boards along with lighter, more flexible, yet warmer wetsuits. (The rapid growth in surfing's popularity north of Santa Cruz - especially around SF @ Ocean beach - is due in no small part to these trends.) As for hiking, we can see the trend/impact in advanced lighter/stronger materials and increased loft of down bags/jackets.
Now, let us consider what some (including myself) would consider the most pleasant hiking experience: just walking along on a nice day hike with your dog, S/O, kids, friends, etc, with maybe a light windbreaker and a day-pack with some snacks, water, etc, and not too much exertion so you can engage in conversation, etc.
The question then becomes (using my definition of the ultimate hiking experience), how to scale it for longer, more remote, rigorous hikes? IMO, your pack should be the last consideration; rather, one must address two core issues: (a) keep warm; (b) keep dry. Practically speaking, given the advances in material science, it's fairly trivial to satisfy these two items with equipment/clothing that are both very lightweight and highly compressible.
If all we have to do then is add the commensurate amount of food for the expected duration of the trip, along with some other essential items, then many people might be surprised at just how little pack space and weight support is really required for a multi-day backpacking trip. At this point, pack considerations come into play. I actually played around a few times seeing how much stuff I could pack into my generic daypack. The end result was I realized I actually needed around 25-30L.
Material like Dyneema 140/210 were all developed for military specifications (as well as GoreTex, ad infinitum) In fact, backpacking, like many other things, owes a ton to military R&D. (Wetsuits were developed by the Navy - it took Jack O'Neil to realize the potential for surfing.) So, if all you need is a 25L+ day-pack with material strong enough to carry the (minimal) load, why does it need/require any extraneous attachments like a hip-belt and/or sternum strap?
Even better, if you know how to sew, you can handcraft a custom pack (along with other equipment) tailored to your exact specifications that can significantly increase comfort and durability. So, to inversely answer your question, it's really just about achievement - knowing you are doing "some thing" at its highest, most refined level of execution possible.
If that's not your bag (pun intended), then I would agree it would seem to be unimaginably boring when one can just throw on any old pack, stuff in a bunch of clothing/equipment and go.