I dont think Federer is arrogant - afterall he is the greatest player in history and deserves respect.
It was obvious that Andy beating him five years ago got up his nose and he wanted to put this
young "upstart" in his place. When Andy continued beating him he got even more annoyed because at that time he could beat almost anyone with his eyes closed and he did not need to go all out when playing youngsters - but when playing Andy he did have to and he didn't want to. Also Andy's game was different and Federer I feel couldn't be bothered to adapt to it. Now he has to.
I think his certain smugness is only natural. He has proven the point that it is not easy to be a great champion and that greatness is not bestowed on a player overnight.
I don't like blanket statements. Just because he has 17 GSs doesn't really mean he's the greatest of all time. As I've said a number of times in the past, numbers don't lie but they never tell the whole truth either. Federer has a lot of grey areas in his entire career and if one is really interested, they can always do a bit of research and find out.
As to your second statement, no, smugness is not natural. It's purely made up. Surely he can't think his achievements are bigger than the likes of Mother Teresa or Mahatma Gandhi etc.? Do you think their paths were easy? Yet the difference is night and day. It's completely within your reach to stay grounded and it almost always comes down to what you choose in the end. And he chose to be an arrogant prick.
And it was easy for him because the era he stepped into back in those days was the era when tennis was seeing its lowest low. He simply capitalized the situation and he’s still doing that.