I use both the Hansen trays and the Craftsman plastic rails. I also have a tray that is mixed SAE and Metric on the same tray and the Lisle magnetic trays. Why?
First, the Hansen trays make finding a socket quick and easy and if needed I can take the tray to the work. As mentioned they do "waste" space but the access and organization seem worth it. I appreciate being able to spot a stray socket instantly, but the gaps and mis-match sizing are annoying. I have similar good and bad feelings with the Lisle trays. Second, the rails seem better for torx, hex, flex and driver sockets.
Build us a better mouse-trap. From all the endless debate and opinion regarding how to organize a box generally and sockets in particular, the market is there! Also, please ponder the wrenches, screwdrivers, pliers, hammers, punches, chisels, and ratchets, extensions, speeders, flex handles and all the other tools that rattle, roll or flop about in the big chests, little boxes, walls and benchtops in all the garages of this world.