It's a function of the HN echo chamber. I used Bootstrap to quick do something at work, and everyone loved it. They've never seen bootstrap, or anything like it before. These are technically inclined IT people, but they're not bleeding edge like HN.

I personally don't care about the styling, so long as there's visual flow. We can all pick Wordpress out of a lineup, but do you go "eww, Wordpress"? I think too many people try to use Bootstrap as a substitute for visuals rather than trying to leverage it to fit their content. I believe you can do that even without tweaking the stock color scheme.