I suppose the curriculum for LA is just too large for the time it is given and, therefore, professors just ended up having to shove formulas as fast as they could to make ends meet.

Another view is that they themselves learned like that and are as much victims as we are. It isn't because the guy is a professor that he knows the intuitions by heart. It is easy to blame professors, we always start our argument by assuming they knew it all and just pretended not to.