The 9 Ball rack is supposed to be random with the exception of the 1 and the 9. This is what I always do unless my opponent gives me a reason to do otherwise. If I notice they are going out of their way to rack a certain way for themselves (in rack your own) or doing the same against me (opponent racks) then instead of having some long drawn out argument about it, I will just return the favor.
I think the term "pattern racking" is a relatively new term. Players in the past would make sure not to put the first few balls in ideal positions for their opponent (1,2,3) but I'm not so sure this was considered pattern racking. I recall in one of Mike Sigel's instructional videos years ago he went over the idea of separating the balls in the rack so as not to give your opponent an easy layout. I don't think this was ever considered pattern racking. I think most players did something like this. It probably was against the official rules but I think most players practiced this to some extent.
When I think of pattern racking I think of what someone like Donny Mills or Corey Deuel do. Where they put all the balls in the exact same place and break the balls exactly the same way in order to get the exact same PATTERN. What we are talking about isn't really this, especially since we are most likely talking about players that are breaking the balls pretty hard and not nearly as predictably as Donny or Corey are capable of. So basically if you can't break really consistently the idea of pattern racking becomes a moot point for most players.
So I think there's a difference between actual "pattern racking" and not putting the balls in the rack randomly. They are probably both against the rules but I think the 2nd one is an unenforceable rule and it's a rule that's not worth arguing about anyway for most of us.
***Edit***
So I voted other because I don't think we are really talking about pattern racking.