I think (2) is on purpose. It's a fundamental result of queuing theory that if demand is 'lumpy' you have to put with either long lines or idle resources.
Most places choose long lines, but Apple seems like the sort of company to choose to have people some people idle most of the time rather than have long lines some of the time.
As Sam points out below: it is especially aggravating if you're getting slow service while 20 blue-shirted staff are standing around doing nothing. Intellectually, I understand why that might be happening: those people don't have roles that enable them to check customers out. Emotionally, it feels like (a) nobody at the store cares, and (b) that I can't get any bead on when or who or how someone at the store is going to help me.
My general point is, I can imagine how a seasoned retail pro might tour a bunch of Apple stores and come to the conclusion that they are haphazardly and wastefully staffed.
I also buy any argument for that conclusion being wrong! I'm not a retail guy. But do note that, like many other people who will chime in on this thread, while the Apple retail experience isn't bad per se (it's much better than shopping at Best Buy), it can in reality be very annoying. They have room to improve.
Most places choose long lines, but Apple seems like the sort of company to choose to have people some people idle most of the time rather than have long lines some of the time.