Why would you assume it's an emergent property and thus should be dismissed as not being a force of nature? I'm making fewer assumptions than you are by wanting to list it alongside the other forces until we can determine if it is emergent or not, and the implications of such emergence. It's kind of a big deal that we can sit here and ponder the forces of nature with some degree of control over our little sack of atoms.
It's safe to say that this list is going to change over time and represents a current snapshot of humanity's limited understanding. Under the current snapshot of human understanding, leaving it off of the list seems to me to indicate an ironic bias on the behalf of researchers who must use the very force in question to do anything. By necessity, it is the overarching phenomenon surrounding all other forces since the only place we can definitively know these forces even exist is within our own mind. To say anything more is to make assumptions.
While I agree that a certain level of assumptions are necessary if we're going to get anywhere, I'm also acutely aware that they're still assumptions and that assumptions are not scientific. If we're going to be scientific about this, we need to make as few assumptions as possible.