I wouldn't exactly describe Tennant as quiet and tantrum-free. His arrogance and hostile attitude were very evident in "The Sontaran Stratagem"/"The Poison Sky", and "Midnight", and that's just off the top of my head. His actions in the former pretty much shot to pieces the respect that Colonel Mace had for him, to the point where Mace simply shut him out to a degree. And, his actions in the latter didn't help matters, and he ended up in more trouble than he would have been had he simply approached things a bit differently.
Plus, being techy goes along with the elderly persona. Hartnell's Doctor could get quite shouty and was often arrogant and impatient. Tom Baker's Doctor was also often arrogant and could get very snippy and prone to bouts of righteous anger. And one of my favorite Doctors, Colin Baker, is one of the most shouty Doctors ever. Eccleston's ninth was needlessly hostile towards Mickey Smith, and called humans "Stupid apes" or "stupid little people" on more than one occasion.
I've watched Smith quite closely, he's no more prone to denigrating the humans around him than any of the previous Doctors have been, and in some ways, less so. I'd much rather be told to shut up than be called a stupid ape.
You don't like Smith, and that's fine. But I think you're overstating his temper a bit.
"Fraud doesn't pay. Especially if you're an idiot." - Rhinoxchris parasyte - "Seriously, what car company is going to want their car released with the name "Breakdown" on the box?!"