However, it was - at the time - his ship, the same way another Admiral - James T. Kirk - got the Enterprise from another Captain (William Decker) and changed things to his own specifications. Each commander is different. I'm sure if Sisko took command of the Enterprise or Admiral Janeway took command, things would be set a certain way until the crew became familiar with one another. Interestingly, in Season 1 Picard was a bit of an ass anyway, and not just certain episodes. He changed into speechPicard - albeit still self-righteous - in later seasons, then actionPicard in the movies.