Arrogance does not always mean a bad attitude. In a lot of ways arrogance is a very good trait for motivation. However, it can prove problematic if not managed right (United probably being a very good example, both as good and bad over the last 30 years and more recently in the last 10).You may like arrogant players. Pep does not. That's what matters.
However all personality traits need to be managed and it’s a skill of the manager and managing staff to do this.
Not buying a player purely on being arrogant would not show much vision, but the personality of the player and the effect on the team should always be discussed.
For the record I think he’s going Madrid, but any team who could afford him and he wanted to join would do the deal (arrogance or not) because the trade off with skill set is so worth it!!