I always took Ax's arrogance as partially being because he's young. Also, you have to remember that he is essentially marooned on an alien planet. Of course he's going to cling to his culture and defend it and if that means being arrogant, then so be it. There were moments, though, that Ax was seriously disillusioned about his people (for example, remember when he was made to take the blame for Elfangor giving the kids the ability to morph). I think deep down Ax was seriously conflicted at times, and very lonely, and the arrogance was sometimes real but a lot of times simply a cover. It's like the person who uses anger to cover the fact that he's afraid.
Two thumbs up!
When Tobias morphed Ax, with the Andalite's body came its raw sentiments of optimism. Optimism that when shift and shaped by circumstances of war can unfold into arrogance, me thinks.
Prince Seerow had judged himself a worthy teacher to the helpless intelligent Yeerks. Since then, how long had the war been going for until Elfangor's early days? The war factor may indeed come into account with their people's arrogance.
Ax is the latest generation, fully growing up in his Homeworld under these circumstances. He then gets stranded with aliens on Earth, who have their own set of values. I am sure the 'arrogance' thing is only due to a comparison between the two species. Swap places and revert the situation, and what would the Andalites take humans for?