Why aren't the passenger seats designed as jump seats (foldable) in commercial airlines? We know that the crew seats in an airplane are "jump seats (foldable)", which made me wonder why it isn't the same case with passenger seats.

Some advantages which I see if passenger seats are converted to the "jump seat" design:


Better access and thus easier cleaning of the aircraft
Easy entry exit by passengers
Already available tech (as in the crew jump seats)
You're in luck. Airbus has filed a patent for that. (Not a joke.)


  Airbus said the design was a response to recent demands from low-cost airlines to cram more seating into existing plane interiors – often to the detriment of passenger comfort.


Just when I thought the below can't get any worse.

(Original, sardine edit by @TomMcW)



There is also this concept:




  Although the patent has been filed, whether or not the seats will become popular depends on whether or not airlines want to pick up the design.