All this is true, and so on. But the in all the plus points outweigh the minus points, you are getting a £37000 premuim small SUV for 6.5% of the rrp. The quality of the interior, the tech and the street kerb appeal. Where i live there are lots of takers for this car, many school run drivers(in normal times) wanting to show off their premuim suv’s!
When working out your calculation you seem to have forgotten the PIP (or equivalent) that you are sacrificing in addition to the AP (almost £10k over 3 years), which means that you are paying more like 34% of the rrp, not 6.5%. I get the point you are making though. As a general rule, the more expensive the car, the better value it is through Motability. Those getting small runabouts, even with zero AP, can be paying 60% of the rrp (as the same £10k is sacrificed, regardless of choice) and may in some cases have found better value by going private!