Nice to see people standing up for the drivers here. I'm no Ryanair fan at all and frankly its hard to defend landing an airliner without clearance, BUT...
The list of "but"s is a long one.
On the face of it an incident like this is likely to be rooted in either complacency of a surprising degree, or fatigue. We've all been there, and I'm sure we all read this tale with a slightly smug but sympathetic feeling of "Jeez! Glad it wasn't me!"
Landing without clearance is rightly regarded as a serious error but on a realistic scale of added hazard its some way down the list. Lie somewhere near the bottom imho. In good vis and assuming usual visual alertness its a pretty much no-extra-hazard event isn't it?
Problem arises when non aviation people (the meeja-led pubberlik) assume that everything a pilot does "obviously" has to be "with permission" in order to turn the event from immediately fatal to perfectly safe. Its a report bred of a fundamental lack of understanding and also the emotions based on scores of hollywood derived assumptions. eg the spurious crap about listening to emergency channels during landing. How many dangerous situations would we get into if that were a regular feature of our approaches - I'm thinking "practice Pan, practice Pan" all day long in summer UK.
Sadly my company (not too far from Ryanair) had SOP'd out of existence the vital ability to incorporate landing light switching as an aide memoire, this being part of the endless drive to destroy Airmanship in the name of conformity.
Dutch Capt, 22yr old FO, you have my sympathy in your current troubles, esp given where the incident occurred.