despite what many people seem to assume, this forum and others like it represent only a small fraction of Poser users - the tip of a very large iceberg.  the vast majority of Poser products are purchased by an 'invisible majority' - people who never post in the forums, never post an image, and you have never heard of.

even if every single person that posted in a request thread purchased the product (and they wont - far from it), you are still looking at a fraction of a percent of the Poser market.  while it may be lucrative for not-yet-established merchants to make niche products catering to request threads, the sad reality that most of them soon realize is that they stand to make very little money for the time invested. almost every merchant i have spoken to has some experience earlier in their career where they made some obscure or niche product based on requests and enthusiastic urging, then had it sell pitifully -- to top it all off often the requestee doesnt even buy it.
...not to mention then the poor merchant is stuck with something like 'Candy - Photorealistic Hairy V4 character with Armpit Hair and Wild '70s Bush' in their store.

so the decision between making mainstream products that cater to 90% of the poser market and making niche products that cater to at most 1-2% is pretty straightforward -- and you cant really blame merchants who have bills to pay for making it. not many have the luxury to so severely limit their potential market. most often the only niche products youll see are from hobbyists who do not need the money and are making products primarily catering to personal interests/passions.
that said, i do believe that if you make mainstream products they should still be different (whether it be style, quality, function, whatever) than everyone elses, otherwise whats the point.

youd get more niche products made if people would actually make some sortof minor commitment to buy, so that the poor merchant that goes out of their way to make it actually gets compensated for their time. this would be an excellent venue for less established merchants to have some guaranteed income and build up a name for themselves.