As a very, very frequent flyer over the last ten years, I would agree with the OP, the Ryanair check-in experience is overlong and loaded with questions already asked at time of booking. It smacks of Mrs Doyle to me and irrespective of whether or not I can click no thank you multiple times, as a customer experience it is less than engaging. They aren't the only perpetrators of this upselling approach, booking flights with BA recently I noted the same eagerness for me to take advantage of various offers that they had to make. Needless to say, they got the same response that Ryanair do.
On the bash/defend Ryanair that these topics always seem to drift to. For the most part, I have had fair to reasonable service from Ryanair, most staff have been courteous, most flights have flown and have operated reasonably on time. Furthermore I fly frequently enough to be irritated but not put out by the various zealous campaigns that their management institute to squeeze the last cent out of the client base. However, as time has gone on, I am less and less inclined to fly Ryanair, while I am not excluded by their busy website, their cross-selling, their up-selling, their strictures, etc, I am put off by it. It is a little bit of extra hassle and irritation that I would have to encounter every week if I was flying with them and, as other posters have pointed out, the price is far from always right.
So as time has gone on, Ryanair have worked hard at it and lost me as a regular customer. Once I chose to fly with them weekly, now I only do so when I really have no other option.