My view is this...
Rucksacks above 60L capacity used to fit into a couple of categories:
Backpacking generally they had a couple of side pouches sewn on so you could have useful stuff to hand during the day..
Climbing which did away with the side pouches as they might cause problems and snags if you're hauling the sac or climbing up a chimney or corner with it on.
Below 60L were Daysacks and 45L was a big daysack for Winter or Alpine trips and 35 L being the norm for Hillwalking and days at the Local Crag...
I think the current propensity for stuffing a 35L daysack with kit has its roots in the following.
1. Ray Jardine and the Ultra lightweight Backpacking movement. Less kit and lighter kit can make for a smaller pack. Lighter kit means you can travel further for a given energy input.
2. The Know More Carry less Ethos of 'Bushcraft'.
Point 1 makes sense and in some ways mainstream outdoor kit suppliers are catching up with the UL movement. So what was a 75L load 10 years ago if you pick the right product can be reduced down to 50L or lower. Kit is forever getting lighter and more compact.
Point 2 is interesting. Fundamentally in an unrestricted environment with enough knowledge and skills it should be possible to get by with natural materials and a few bits of vital kit to enable + enhance this. So for example don't take a tarp build a shelter, don't take a roll mat use leaves as insulation, don't take a sleeping bag or cooker use a fire for cooking and warmth at night. So a 35L daysack in this situation probably is enough to carry this vital kit.
I think the overstuffed 35L sack with pouches all over it is a result of a desire to live the 'KMCL Ethos' balanced out with the reality of having to carry stuff as the unrestricted environment does not exist. In addition Bushcrafters seem to like 'Army Surplus' as it's: green, tough and low cost. Often however it can be bulky. Which is a problem if you're trying to pack into a small space.
Another point that gives you problems with low pack space is for example the fact some sub set 'Bushcraft' activities such as Temperate Climate Hammocking actually require more kit to do.
A 'Ground Dwelling' Tarp Shelter Generally needs:
Tarp, Sleeping mat, Sleeping Bag.
Hammocking needs:
Tarp, Hammock, Sleeping bag, Sleeping mat, Hammock suspension kit.
As an absolute generally agreed minimum...
If we assume the same Tarp, sleeping bag, sleeping mat for both systems then we can see were going to have to have more bulk and weight with the addition of the Hammock and suspension kit.
I guess then finally you have the fact that a Pack with MOLLE and lots of pouches stuck onto it looks tacticool Nothing wrong with that. It doesnt rub my rhubarb but some folk are fine with it.
My experience which shapes my view is that a Rucksack of 60L + is better for backpacking with normal kit and one of 35-45L is generally fine as a daysack.
Folk will do what they will.
