In the picture, the harness isn't adjusted correctly -- it's too high relative to the pack.
My goal, even with an unbelted pack, is to load the lumbar curve as much as possible to relieve weight from the shoulders and make life easier on the spine. Loading the lumber curve also has the effect of moving the Load Center of Gravity closer to the body center of gravity which makes for a more comfortable carry. In general I'm trying to get the bottom of the pack to ride even with the belt line regardless of pack height. The Tarahumara is kind of an exception because it is so small that it's reasonably comfortable a little higher on the back.
Moving the harness lower on packs in the 19" and shorter range effectively moves the pack up the body which is an ergonomic disaster. It guarantees that only the shoulders will be loaded and the mid spine will become a fulcrum for an unwieldy mass jutting out from the shoulder blades. Load lifters won't do a thing to help the situation on a pack that short.
I'll only start moving the harness down the pack and adding load lifters as the pack gets taller than that 19" range. That lets the bottom of the pack be where it should but the top of the pack is starting to climb above the level where the harness naturally needs to go on most bodies.
This picture from our Pack Fitment page illustrates the concept:
The stay is essentially the height of the pack and the bottom of the stay is the fixed position where I always want the bottom of the pack to ride. You can see that the 19" Umlindi in your first picture is still short enough that the harness needs to start at the top of the pack. When you step up to that 21" height, the harness now needs to ride lower than the top of the pack for the bottom of the pack to still be where it should.
One additional point -- all of our packs are torso height adjustable because it's so important to get that bottom of the pack to start of harness dimension correct for maximum load carriage. The Umlindi is actually borderline. On shorter people, it can't quite be adjusted for as short of torso height as need be. However, it's a special case as it was designed to be the largest belted lumbar pack practical even though it works well beltless. As soon as packs get tall enough to drop the harness lower and use load lifters, I drop the harness a lot lower -- 17" on packs that can be run either belted or beltless, 12" on packs that are only meant to be run with a belt.