A couple thoughts...
1-I love that the Cardinals did not the fear of losing Ray Horton keep them from taking the guy who they thought was the best match for the job. It is the same reason I have no problem trading a player in dvision if it gives you the best deal. When you make decisions based on fear you limit yourself the ability to make the best choice.
2-I like the Bruce Arians hire because it addresses what we need to fix the most, our offense and our QB. Arians is a guy with a ton of talent developing young QBs. I am sure he has his warts, but in the end, he had a hand in developing Manning, Roethlisberger, and Andrew Luck. They had talent, but he helped them adjust successfully to the pro game.
3-I don't love Horton being replaced by Todd Bowles, but I am not scared of it either. Horton helped coach our defense to become a very good unit. However, that unit was never a dominant or very physical defense. We are losing a creative and finesse defense which struggled against the teams in our own division. I am not trying to say Horton did not do a very good job in Arizona, but I do believe he is replacable.