Yeah I know they do that, but I also have been on many Ryanair flights which were full wall to wall, and it didn't seem to affect the CofG then.
Since a couple of days before my flight you couldn't but a ticket for it, I assumed it was full. It then turns out there were at least 80 empty seats. So why couldn't you buy a ticket then ?
Only reason I could come up with, is to make room for fuel and or cargo.
Given the cost of fuel in Latvia (£ 0.6 per litre at the petrol station) I assumed that Ryanair might make more money carrying fuel from Latvia rather than taking passengers at £ 1.99 per ticket ?