The variation, I think, is due to different metaphysical assumptions. The relegation of metaphysics to mean nothing more than "spooky woo stuff" has been the cause of more sloppy thinking… but don't get me started on that.
In the traditional "element" metaphysical structure, fire is associated with emotion not for arbitrary reasons, but because fire is seen as literally the same as the emotions. The decoupling of that, due to modern physics determining the observed structure of literal fire and disassociating it from emotions, created a new metaphysical assumption, which is what, I presume, you use. Some people chose instead to posit a metaphysical system in which there are levels of existence ("vibratory planes", the Kabbalistic "worlds", and so on) in which various items appear differently, but are metaphysically the same. So, in the material vibratory level, fire is what we observe, while in the mental vibratory level, fire is the substance of emotional states, and so on. If you assume a naive materialist metaphysic, such as the idea that consciousness is a byproduct of complex material/energetic interactions, then those associations are arbitrary, indeed. If your metaphysic instead operates on the assumption that things have layers of reality, then those associations become more observationally-based. There are, of course, other metaphysical assumptions that can apply, but it is important to understand what those assumptions are, whichever set you choose.
@Faoladh I think you've nailed it on the head. And I agree with your take on metaphysical assumptions.