To my mind, there is nothing wrong in Ryanair's basic model. To provide cheaper services for a broad public. Giving pax the opportunity to save on flying, to fly more often, to spend more money at the destination, less for air travel.
There's also nothing wrong in using these minor airports, as long as on another side of the route exists a bigger one (a base presumably). It's cheaper to use them, many smaller airports are very pleasant indeed. The vicinity is sometimes very beautiful, tourists are always able to find more or less fascinating attractions nearby. Local people are keen to have better links to other places in Europe too.
The carrier has been able to exploit this very well and has grown rapidly. What has been disregarded by FR - it's the need to adjust the model to the changing environment (the level of competition, saturation of the market, more demanding and less price-sensitive passengers reacting on other type of inducement than cheap propaganda MOL's style, and so on). Some kind of face-lifting operation still can be done, to get more clients (and to keep the old ones). In fact a kind of re-branding has to be implemented pretty soon, if Ryanair want to sustain the growth.
Nowadays, the lack of customer care is much more disturbing and jeopardizing the entire model than any government tax (unnecessary, true, but used as an excuse for everything). It's not so expensive to change that. Why not surprise us in a positive way?