Because you’re creating a load of extra faff and limiting your choice of products to solve a non-existent problem.
What are you on about? I just explained exactly why I might need to take off the rack and put it in the boot. Whats the other option, leave it on the ground or block a road? I can think of a couple of places I go to where you would park nose first into a space and the rack would then poke out too far for other vehicles to pass. It might not happen very often but if there are two similar products and one folds up easily and can go in the boot that would be a handy feature to add. Sounds like the Atera does exactly that. The other good looking option is the Witter one pictures above.
What is the extra faff you speak off?