I can only speak for myself (as a dev), but the times I have proposed/discussed this with my patrons, the majority was (very) opposed to this. I can appreciate there are people that enjoy this, but so far it seems to be a (relatively) small group.
And the problem with creating optional niche content is that it takes a lot of time, but doesn't appeal to many players. And I get enough flak for the "lack of content" as it is
Aside from that I personally just don't enjoy that type of content as much as a dev, but I would have no problems with it if I know it would be something a lot of people would like to see (in contrary to some of the requests I get).
I do intend to introduce less "vanilla" content in the final stage, but it will still be in the form of a poll. So I guess the more "mainstream niches" will get the most votes, making that a bit of a contradiction on its own.