A few comments:
A dictionary is vastly more than a “history of past usage.” It is a cultural touchstone. This may not be apparent to those without high degree of mobility, but the existence of dictionaries (and especially inter-language dictionaries) is critical to the ability of complete strangers (even in the cultural sense) to interact. I think we universally underestimate the extent to which our culture enables our “meaningful” interaction.
Your last sentence is right on the mark—we can start inventing all sorts of new definitions but we need to be very careful that we don’t stray too far into our own language. We might corrode our ability to interact meaningfully with life-giver “society.”
I have noted a very large number of multi-meaning words in english—note, interestingly, that Japanese has multiple kanji representations of words with similar, but not equivalent, meanings and same readings—e.g. 見るvs.観る both being read “miru” and the first meaning “to see” (e.g. to see a tree) with the second meaning “to watch” (e.g. to watch a movie).
By this point the intellectual community (and especially the philosophical) is sufficiently diffuse that very very important words (e.g. “context,” “content,” “concept,” “abstraction”) have lost their meaning or become tremendously blurred.
Your point that the fight to define a word is really the fight to assert a moral position/worldview/what-have-you is extremely interesting. I hadn’t thought about it that way.
It immediately brings to mind the question of “how do we define definition?” which is infinitely interesting. If we define “definition” then we must necessarily be doing so in a context that is removed from the context in which we are defining “definition.” This immediately implies that there is no universal sense in which words can be “defined” but that there are infinite senses in which words can be “defined.” When two entities conflict on a definition they are both thinking in contexts which are removed from the context in question (e.g. the characters thinking about the tree are arguing about the correct procedure for creating a common-usage definition). But most people do not think in this meta-context often which is why they have woefully underdeveloped vocabularies and theories w/r/t it. Thus, frustration. Thus, anger. But it’s just a silly tree!