The benefit is for the prespective 2 million buyers who are trying to make plans for selling or keeping their old truck for another year or six months.
Consideration for your potential owners may not be good business anymore. However, details are needed and would be quite helpful in decision...
Based on this older Cybertruck spec sheet it does not appear to be a 5% shrink. Its about the same length, wheel base a little shorter, and actually a little wider now! Of course the accuracy of this spec sheet is to be questioned. I'm just saying I don't see the "smaller by 5%" here.
On the original Cybertruck model the rear top glass appears to lineup with the vertical line of the back door. On the new model the top glass/divider seems to be about 6 inches beyond the vertical line of the back door. I imagine this slight change will cause a redesign of the Cyberlandr.