Jippie - I agree that those going away for more than 2 weeks will need to find a printer. However, in most towns in Europe it is usually pretty easy to find an Internet cafe or public library, particularly in areas that get plenty of tourists. Do remember, that Ryanair doesn't fly to anywhere *that* remote in Europe.
Alternatively, if one is staying in a small village for 2 weeks on an annual summer holiday, it is quite likely that the hotel or campsite will provide a few PCs for the guests to use for a small fee. If you're really desperate, ask at reception if you can borrow their PC for a few mins to print a boarding card.
I would imagine that most people who can afford to fly around Europe will not want to lose access to email for 2+ weeks anyway.
Yes, there will be a small number of people for whom finding a printer might be very difficult, but the saving of no check-in desks should more than outweigh the loss of a small number of revenue sales