al446 - Thats not a very nice thing to say. Taking a bag is an option, but some people are overweight not cause they choose to, but they may have any kind of disorder.
Besides, the main problem for Ryanair isn't exactly the weight itself, but the fact that the more bags there are on a flight the longer it takes to load and offload them, that may contribute to a delay on the tight 25min turn arounds. Plus, more bags mean more check-in desks and baggage handlers.
I agree with you on the part of passengers wearing loads of clothes to not have to pay for a bag and check them in.
Going away with them next week to Brussels. Already checked-in, just taking hand luggage with some clothes and a jacket and ready to go. More than enough for a few days.