Lionel's uninformative - to civilians - item number system has been an irritant to many for a long time; maybe forever. To those of us who are former catalogue junkies, and Hi-railers since dirt, it has not been a real problem, but to the newbies and those who have a real but more casual "internal data base" the numbers are no help.
I agree it is helpful to understand Lionel's numbering system. But there is good reason for Lionel to keep it to themselves, at least officially. Were Lionel to publish it's numbering system, then their ability to modify as needed would be severely impacted. They'd be bound to announce changes, and then listen to the cries of people who think it shouldn't be changed.
Plus, how many of the posts here are critiquing / criticizing the scheme?
I am certain the folks at Lionel put plenty of thought into it.