Lacking "polite fluff" is the least of the problems with that email...
"Dear" and "sincerely" sound much too formal to me. Some sort of "hello" is polite if you're the one opening the conversation. I almost never include a formal valediction, and usually not even an informal one.
I have to agree on this level of formalness being unnecessary for most business correspondence. Speaking of businesses outside of bitcoin, I tend to get a little suspicious if the person is being too 'nice'. It makes me wonder things like, "Do they really need my business that bad, or, are they up to something". The closing sentiment should not be much more than 'Thanks', 'Regards', and at most, as I get from a lot of Asian correspondence, 'Kind Regards'. The later would probably be creepy if coming from a US business and would bring back my suspicions.
That said, the body should never carry tones of defensiveness but this is not a Bitcoin product. I had a response just the other day from a sales manager at a very large distributor that had a lot of defensive undertones in it. It was in reply to my directing a question of his repsonse time on a quote back to him AND his boss. ;p Hey, I was told 24-48 hours for a quote and six days later had not recieved one. On that same note, I made sure my reply did not 'feed' into that and was straight forward with my intentions.
TL;DR All people are subject to unprofessionalism, not just Bitcoiners. And, it takes two to conduct business profesionally