Actually had it set as required reading in high school English of all things.
Esperanto is an attempt at a equal international language for all. http://en.wikipedia.org/wiki/Esperanto
Because English and English speakers are happy to adapt and change, the simplification is happening. Look at text messaging where superfluous extra words and letters get dropped, as does case. Even Hollywood is careful to keep language simple in their popular movies aimed at a worldwide audience.
> I don't see how it holds any more weight than your argument from antiquity
The dictionary is nothing but "argument from antiquity", as would be the conventional definition of "correct usage", in contrast to the "many people doing it wrong makes it right!" definition you disavowed, skipped a graph, then repeated.
Prepositions are not "essentially arbitrary" even when used with metaphysical concepts. Particular prepositions work with particular types of concepts, and curiously, end up quite similarly used among a variety of cultures and languages. In English, for example, is the concept something you can possess, or a process that happens to you? If you consider other things that couple with "on" or "by", you'll see what I mean.
Certainly English is charming, and rapidly evolving. You've likely read Bill Bryson's "The Mother Tongue", but if not, you might enjoy it.
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