How come the humans in the pokéverse use spherical pokéballs to hold pokémon despite their obvious inferiority to pretty much every other shape?
>less efficient use of space compared to, say, cubes
>easier to drop than other objects
>will roll away when dropped
>will roll away when put down on anything other than a perfectly flat surface
>opening/hinge mechanism probably wouldn't be very reliable and could feasibly fail. What if you dropped a ball with a wailord inside and it shattered, causing him to materialize inside your house and tear it apart?

We know they have other options (Sir Aaron put Lucario in a scepter in his movie and that was hundreds of years before modern pokéscience) so why do people keep using these things?