Why can't the English consider unlearning how to speak, in service of greater good and just because?

Do any of you understand why a proper English sentence must not end in a preposition?

I think I could muster up a little reasoning behind eschewing split infinitives (though I freely acknowledge that for me the true attraction is all in the novelty of it: rebelliously to order my phrase - to order rebelliously my phrase - in a way that just sounds cool because it's different from what I'm used to hearing - to rebelliously order my phrase). And I'm all over the imperative value of making distinct through writing the homophones - its it's your you're their they're there then than - like white on rice. (Though my well-educated friend K tells me there's a raging argument amongst philosophers as to whether this is an issue of grammar or spelling. To which I believe the proper reply is whatever.)

The dangling participle rule just makes sense. "Dangling out there in separation from its antecedent, I find the participle confuses the reader's understanding of the subject." Dangling I ain't. The sentence doesn't make sense when the participle dangles, and making sense usually makes for good human relations.

On the other hand, I would argue vehemently in favor of abolishing the "don't refer to the singular subject or object 'one' with the plural they or them" rule, on value-based grounds. Gendered pronouns exclude, historically, culturally, subliminally, and inexcusably. If one believes a contemporary case can be made for "he" including me, then I submit that he is married more to the letter of the language law than to the idea that language was made for people, not man for the word-(style)-rules. (For it is style I believe that dictates this rule, not reason the value of clarity.)

But, I just can't seem to grasp (or remember?) why we're not to end our sentences with an of, about, in, etc. Is it just because?

Srsly, if understanding, harmony, love, joy, peace, truth... may be achieved through the more proper ordering of my words, then pull me back from those slippery slopes of grammatical rule-shifting . If not, then, let's all hold hands and redeem the rules of grammar from the paralyzing grips of arbitrary absolutes and let's not be scared of a little slipping and sliding on the slopes of a living, loving language.