'I can only assume that these rules were broken so many times that the "grammar police" decided "if you can't beat 'em, join 'em" and changed the rules to fit in with the de facto usage of the language.'

Possibly, but that's beside the point - the rules were wrong in the first place.

I'll tell you all a little secret: not everything you were taught in school, even to the tune of a hickory stick, is right. Yes, two plus two does make four. No, there is nothing intrinsically wrong with ending a sentence with a preposition.

"So to frequently split an infinitive is probably allowed these days, even if it seems somewhat inelegant."

It seems inelegant only to those to whom it seems inelegant.