What is to be had by calling this a 'cognitive bias'? That is to assume a prior and universal value-set. In matter of fact, it is perfectly natural for people to value their own creative activity. That is central to what it is to be a human.
> Researchers then priced the items the experimenters had assembled as well as pre-assembled IKEA furniture. The results showed that the subjects were willing to pay 63% more for the former than for the latter.
And it's clearly not rational. As long as you assign positive value to your time.
If time has positive value, then so do objects with time invested in them.
I mean unless assembling it is something that you really enjoy doing. So much that you want to pay extra for that pleasure.
I would say it is hard to live a good life if you don't value the things you create.
It is interesting to see that people weren't able to predict this behavior. However, people are unable to predict many of their own behaviors, so that isn't a damning result by itself.