I don't know what else to say besides, you simply don't understand. I think the fact that baggage scanning is being likened to Fed Ex parcel tracking speaks volumes to that point. Two completely different operations, two completely different services, and two completely different purposes.
I guess the main purpose I would see for scanning bags would be for scenarios when a bag is lost and nobody can find it. The only thing is,.. we don't really ever have that problem.. If a bag gets mishandled, it doesn't take very long to discover it and it's on the next available flight. Scanning will not get it there any faster, and I guess to answer your question NO it's not worth all of the added cost and hassle just to be able to tell you what the status of the bag is in the event of a misconnection.
You see, this is where Southwest tends to separate itself from most other airlines. We're not going to take on some costly system that would serve only a negligible purpose. How about we make up for the fact that we can't track your bags by not losing them in the first place? Sound like a deal?