Perhaps I can shed a little light into Ryanair's thinking here...
There are two good reasons why PCSs (Price Comparison Sites - the likes of Skyscanner) are a pain in the butt for an airline:
1. Revenue erosion. The vast majority of customers want a flight on a given day, and will pay the fare for that day - or perhaps one day either side. What the PCSs do is allow people to trade down from a higher fare by sharply changing dates - not good for the airline. And yes, some people just want to fly (like the original poster) but customers like this tend to be seriously outnumbered by the customers with more date constraints;
2. IT costs. PCSs make an inordinately high number of hits on the reservation system - they are continuously interrogating the airline's systems to price flights, the overwhelming majority of which do not get booked. This makes the systems slower for everyone else using the site, which pushes up the "bomb out" stats - ie, the number of customers who start a booking and then get bored and go somewhere else because the site is slow.
There is also an argument that allowing PCSs to hit the reservation systems like this means that they are building up an image of the airline's yield management profiles - and they are the Crown Jewels in terms of confidentiality.
BTW - re the back end system - Ryanair has migrated from OpenSkies to NewSkies, a move which is being pushed on to Navitaire users, since Navitaire is discontinuing support for OpenSkies. So I guess we'll all have to get used to it!
TA