I do tons of hiring and there is no way I would ever write rejections like that. First of all if you are running a business and doing lots of hiring, there is no way you have time to write that many long thoughtful emails that refer to research you've done on their background, etc. Second, I highly doubt any adult developer gives a crap.

The only thing people want (and appreciate in my experience) is hard, cold facts about exactly where they messed up so they can do better on subsequent interviews. There is nothing that feels worse than failing and not feeling empowered to succeed in the future. As lovey dovey as those examples are, they don't do anything to help the person succeed in the immediate future which is what really sucks about overly terse rejection emails.