I personally feel that, 90% of the time, regular Pokemon look cooler than shinies. If the sprites between regulars and shinies were switched, shinies would be considerably more desirable. "Wow... this is actually how a (cow, turtle, lizard, cat, dog, etc.) is supposed to look! I want one!" This opinion of mine somewhat nullifies the idea that shinies really are "all that," aside from the sheer exuberance one gets from finding one and from bragging to one's friends about having done so.
That being said, I do think that developers should err on the side of making them rarer rather than more common so as to preserve the mystique. However, I feel that newer generations are actually better at this. For example, in Johto there was a red Gyarados and quite a high chance of getting a shiny egg from the Day-Care (though back when my Crystal worked, I never got one). I can't really speak for Black and White 2, never having seen more of them than a brief trailer.