As with almost any sport, there are people tied to it because of status or a sense of traditionalism. Monohull yachting and racing has been traditionally seen as a rich man's sport, with a high price to enter and stay competative. It has also been around for many, many years and is in many people's perception, what "real" sailing is.
Then about 35 years ago these small, inexpensive catamarans started popping up. For the traditionalists, these did not constitute real sailing and also threatened the exclusivity of their sailing. Many of those people would not want to be involved in a boat that you have to set up before you race and get wet and sandy while racing on it. I think a good comparason is thinking of the traditional monohull racing as F1 and the beach cats as NASCAR - a home grown, cheaper alternative but even more fun than the higher priced, technology advanced monohulls.
Over the last 20 years the improvements and advances in cat sailing have been tremendous. A cat with a spin was unthinkable to most 20 years ago and the latest cats are technilogically advanced (in design and materials) to rival the America's Cup racers.
This has been highlighted by the increase in top-notch sailors that are now sailing multihulls exclusively. I think the talent available in the cat classes rivals any other sailing group.
I think that many of the monohull sailors would really like cat sailing if given the opportunity to try one out that appeals to what interests them about sailing, wether it's a boat with wings, a spin or snuffer, or mylar sails and an 18 lb carbon mast. As for the others, they are where they want to be and there will be no changing their minds or opinions, just as many of us couldn't be convinced to leave catamarans to sail only "monoslugs".