Yes, but again remember that for the passenger it isn't a 'low cost experience' one is paying for ... it is a 'no frills experience'. Big difference. All the rest is marketing. The 'low cost' bit is strictly limited to the balance sheet. The range of tariffs promoted to customers will vary according to profit-driven yield management practices. These fare levels are set with the best interests of shareholders in mind; the business is run to give them a healthy return on investment. This is not a criticism of the business model, it is simply a statement of the reality. A low cost base never obliges a carrier to offer cheaper fares than the market will sustain; it just gives them the option to do so tactically. The ability to offer a cheap fare does not imply an obligation to do so. In many instances shareholders will be better served by higher pricing of the product. In the boardroom, shareholder interests take priority over those of bargain-hunting budget travellers.
In terms of your suggestion to shop around for the best deal from the various carriers, that is exactly the right approach. It is just unfortunate that many people less familiar with the industry than regular readers here make misguided assumptions about the competitiveness of fares offered by no-frills carriers.
Moving specifically to the case of FlyBe, it is interesting to note that this company is now marketing different tiers of product with additional 'frills' included at higher fare levels ["FlyBe Plus"]. This is a model which is likely to be more widely adopted by the airline industry going forward.