The five classic Platonic Solids, are the basis of the original polyhedral dice; tetrahedra (4-sided, d4), hexahedron or cube (6-sided, d6), octahedron (8-sided, d8), dodecahedron (12-sided, d12), and the icosahedron (20-sided, d20).
Now days there are specialty dice with more and fewer sides, manufactured for various games. But the classic five are still the basis upon which most game systems stand. These other dice, often referred to as novelty dice, aren't really needed because the numbers they generate can easily be duplicated using the five basic shapes. In our home campaign, we prefer to keep our tables and other materials limited to the basic platonic solids. Though we do include the ten-sider and "percentage" dice for further convenience.
Personally, I admit to being an old Grognard. I'm set in my ways and slow to change, unless given a really good reason to do so (including, but not limited to, being lazy, cheap, or convenience).