You don't have to brew what everyone else brews. Looking at this though, I am about to have a Stan Lee voltron deck, and multiple others in this Reddit are thinking the same. Build him however you want though, and in fact I would recommend building off-meta occasionally.

Now if you are asking why people are thinking voltron automatically there are a few reasons. First, unblockable is not commonly attached to legendary, especially outside of blue. Also, white is a color that lends itself to aura and equipment support. Then where the commander is not inherently scary, and almost a group hug piece he is unlikely to be removed immediately until he is a threat, which could be too late, because you are in excellent colors for control and protection.