I still don't understand the obsession with jetbridges? They slow everything down massively so Luton would basically grind to a halt, especially as they need trained ground handlers to operate them - something that always seems in short supply at Luton, especially marshaller and pushback crews!
With 180 passengers on a full A320, we can easily turn an aircraft with no problems in 35 minutes chocks on to chocks off with two sets of steps a la the Luton set up. Somewhere like KEF/TLV/PMI where we have to use a single jetbridge then you can add 20 minutes onto that easily. In fact turns in TLV are now scheduled to be longer (55 mins) as the company recognise the jetbridges don't lead to a quicker turn.
As you can see from the video you linked, speed of turn is incredibly important to easyJet, and presumably therefore airlines like Wizz and Ryanair. You'll see all three in airports with jetbridges but not using them (AMS for example). So I would suggest that Luton have been listening to their customers who just don't want/wouldn't pay to use them! The only airline I could see asking for them is El Al although they use steps in many other of their airports as well!