I agree, Jack O'Neill in this series is only partly the Jack that was in SG1 and a few guest appearances in SGA. Sadly, he's become "The Man" that he didn't want to become when he took over leadership of the SGC when Hammond got promoted. It's like the writers have forgotten the character they spent 10+ years developing, and Anderson doesn't seem to care either...
It's called growing up. The longer you work for the government the more you become like the government or man in this case. I know because I have worked for them going on 16 years now. No person stays the same in the real world. We all grow or we stagnate as a person.