With little experience I have, I agree that megapixels themselves are not a good indicator of the camera quality. Probably the CCD is. However, we commonly talk about megapixels (together with the year that we bought) to give an idea of the generation of the camera, and that is a good indicator.
Camera brand/megapixels/year gives a good idea to those who 0wn on digital photography, and still is a friendly way to talk about when it comes to beginners like me. We can say the model only, but that's not n00b-friendly