Joe,
Your objection to "off of" is well stated. It's a phrase that is not only ungrammatical but one that grates. Strangely, while it is accepted widely in the USA as a spoken phrase, it is rare to see it in print. I have seen is written but once, and then as dialogue.
What concerns me lately is another "standard" Americanism - "for free". This regrettable utterance has become widespread in Australia over the past two years, initially and continually by the advertising fraternity (surprise! surprise!) and now increasingly by the general population.
When the Americans won their independence, there was a nationalistic move to adopt their own (not English) language. That moved was knocked on the head - or was it?