I think comparing any of the new “bad-guys” cast to the old one is a mistake. In the OT the Empire had been around for quite while, and they were the ones in charge. Even as far as the PT & EU goes, many of these people were in charge during the Clone Wars, so there’s a reason why these are all older more calm and in control characters. Tarkin is a war veteran, a governor (Moff), a general, he’s been a big shot in the ‘Galactic’ Empire for a fairly long time. Hux on the other hand is a young idealist trying to restore something which was destroyed when he was just barely born. It makes sense for him to have an impassioned, Hitler-esque, speech about destroying the enemy. This guy is fighting a much stronger political power and he knows that he’ll have to fight for what he believes in. Tarkin, Piett, Needa, etc. they were all calm and confident because they were already in charge of the world. The Rebels were just a nuisance that they underestimated. Hux, as well as Kylo, has a lot more weighing on their shoulders.

And if you think about it this way, you kind of get the impression that in TFA the First Order, although still very, very powerful, are kind of the underdogs this time around. And although the whole Starkiller Base thing is still kind of a cop-out, it makes a lot more sense how confidently, and efficiently it was taken down. The Resistance is now run by the more calm and in control veterans of the past, and they know what they’re doing this time around. The First Order are the ones trying to catch up in the new trilogy.