It is my understanding that out of respect for the original establishment of the prize, they haven't amended it as an "official" prize, but have essentially fully adopted it - it's just a matter of economics not being much of a discipline when the prize was originally established, no?

Oh, it’s more than lack of familiarity.

‘“Nobel despised people who cared more about profits than society's well-being", saying that "There is nothing to indicate that he would have wanted such a prize", and that the association with the Nobel prizes is "a PR coup by economists to improve their reputation".’ [0]

I’ve also heard rumors that Nobel had a personal animosity towards certain academic areas because of an affair his wife had with a professor, but I can’t find any good references for that.

[0] https://en.wikipedia.org/wiki/Nobel_Memorial_Prize_in_Econom...

I'm pretty sure the latter is as you intimate, incorrect[0]. If it was correct, it apparently pertained to Mittag-Leffler, who is a very admirable human (with an amazing mustache) who was unfairly more or less forgotten[1] outside of complex analysis class.

The fact that the "economics Nobel" isn't a real one, of course, is indisputable[2].

[0] http://almaz.com/nobel/why_no_math.html

[1] https://en.wikipedia.org/wiki/G%C3%B6sta_Mittag-Leffler

[2] for example https://www.theguardian.com/commentisfree/2015/oct/11/nobel-...

According to [1] it is not, even though it is awarded by the same organization.

[1]: https://en.wikipedia.org/wiki/Nobel_Memorial_Prize_in_Econom...