If you can tap into the power of the heavens
Yes, I want to rescind my dismissiveness. If these were any other shape, it would be very tempting to think they just had a practical use. But given that the dodecahedron was an important part of the key to transcending metempsychosis, and as such was almost an object of worship in the early Academy (as Kochiekoch said), it does indeed suggest these objects were not for (some unknown) practical use.
The fact that there were also icosahedral versions seems to solidify the Platonic connection.