I would consider buying a non standard colour as a pet hence answering yes on the poll. It comes down to all of the factors I normally take into consideration when buying a pet which are essentially, health, temperament, and appearance - and especially if I have been "chosen" by a particular kitten. The blue seal mink boy shown here
http://www.oakleybengals.co.uk/ourstuds/ourstuds.htm is one of the prettiest cats I have seen - although he doesn't look anything like a wild cat IMO, he has a striking uniqueness about him that I love. I can see why when he cropped up his breeder decided to keep him as a stud and acquire a blue queen.
There are a few breeders who specialise in non standard colours, and they can also crop up with any breeder from time to time. So for any pet owner who is desperate for one you can always get your hands on one if you look hard enough.
"Undesirable" in the context of the breed standard has nothing to do with desirability to pet owners, many of whom neither know or care what the "ideal" Bengal should look like and quite rightly go for a kitten/cat that steals their hearts. For all of us, beauty is in the eye of the beholder, not what a show judge would think.
Having said that I appreciate breed standards and why most breeders select against non standard colours and not for them. Remember many breeders also like to show, and that may be part of their motivation for staying away from non standard colours. Also I expect there is a "commercial" driver there as brown rosetted cats are without doubt the colour in highest demand.
I guess there has to be a "critical mass" of popularity of a new trait before a colour becomes accepted, and bred on a larger scale. Silver certainly was not accepted when I got my first Bengals, for example, yet now they are highly popular and accepted.