To be the cheapest one? It's important, but not always and not for everyone. A good opinion matters also very much. The carrier need not to have a spotless opinion, but just emphasizing the good record of on time flights is not enough for many. Pax are often frightened more than you can imagine and want to "entrust their fate" to somebody who really cares or at least mocks it well.
I think it's a misunderstanding if the enterprise neglects the diversity among different groups of customers. For example, one can meet some people that would love to save a bit of money, but are too ashamed to accept the marketing style "if you don't like it, f**k off" or simply doesn't want to hear their neighbour asking "will you really fly with that pay-for-loo airline?". The inability to address differing groups of customers is one of the issues Ryanair should re-think as fast as possible.
Furthermore, the markets differ across Europe as well. I also hate taxes, having to pay well over 40% income-tax in my country (with a decent wages of course). But indeed, the 8-euro extra on flights from Germany means really nothing to me and certainly to many else in both Finland and Germany. Is there a reason good enough to slash the frequencies on the extremely well running BRE-TMP route last Summer 7/7 to 3/7 in 2011? It's just shooting themselves in the foot, nothing else, methinks.