I definitely understand this, I really wanted to keep the feature as well it just wasn't in the cards with this new design. Before I made the decision to stop working on a way to get it done I surveyed a couple hundred Exo users and 99% of them did not use the feature. Just about everyone set it at home and never touched it after that. Hearing that, it made it easier for me to drop the feature and focus on other parts of the design. With the better head clearance and 4 frame height options just about everyone will be able to get a perfect balance of load lifter angle and frame clearance (both head and ducking under brush)
Short rant here based off 10 years of obsessive pack designing;
While frame height is definitely an important part of the equation on how a pack will carry weight, it's no where near the top of the list. I'll take a well designed 22" frame over a poorly designed 26" frame any day of the week.
The rule of 80/20 (80% of the weight on your hips and 20% on your shoulders) tells you exactly where 80% of the design should be focused and 80% of your purchasing decision should be based around. The shape and rigidity of the frame itself, how the weight carried transfers into that frame, making sure the frame doesn't change shape when loaded (i.e. barreling), then how that weight is transferred down the frame into the lower, then how the lower (lumbar pad and hipbelt) react to all the weight being transferred into it. These are all vastly more important in the overall design than whether the frame is 24" or 26".
Other factors like the shape and size of the hipbelt / lumbar pad, the foam used, the fabric used, attachment points etc all play very important roles as well of how that weight feels on your body and will perform over time. You can have a great design but use cheap foam and a mile down the trail with 100lbs you'll be feeling it.
The frame height and shoulder harness are still 20% of the equation and important, no question, that's why we have offered frame height adjustments in the past and will continue with the 4 options going forward with K4. It's just not nearly as important as the overall design of the frame and the lower.