That's the business model of most of EU's cheap air companies. E.g. EasyJet "allows" you one piece of luggage on board, but unless you're EasyJet Plus (i.e. pay extra), good luck actually taking it with you on board with any sort of predictability or regularity.
And Ryan Air takes it to a whole new level. At least easy jet planes don't feel like they are going to break in the middle of the flight.
RyanAir doesn't say that you can bring a bag, they actually write the opposite on the ticket, even if you can bring a bag for free.
If you read the little text in the conditions, it doesn't say that you can bring a bag either, instead it adds further confusion to push you to pay an extra bag charge. IMO, the level of deception involved is abusive to the point where it could be brought to the EU court and justify a fine.
That would be my main issue. I don't mind little space and other inconviniences that much ... but I do not accept a higher risk for flying budget. I assumed, that RyanAir budget everything they can, but not savety. And as far as I can tell, the maintaineance etc. looked professional.