The only valid use for these, as far as I am concerned, is when using the chuck to hold a workpiece when working on it, off the lathe i.e. carving, piercing etc. The hub is mounted horizontally so it helps visualise your work in its upright position. This function is mentioned by Axminster but hasn't been raised in this post so far. It also means that since the workpiece and chuck are removed as one, thet can be put back on the lathe without any worriies of misalignment
Using them just for storage is unnecessary expenditure and there are much more cost effective options, as already mentioned by others.