The main reasons are weight, durability & longevity. When metal flake is used there is a gelcoat base, flake & then clearcoat. This all adds weight & build up of gelcoat which induces gelcoat stress cracks since it has no structure. When the sun reflects off of the flake through the clear coat, it burns the clear coat off. Darris wants his boats to last a lifetime, unlike other manufacturers. Plain gelcoat can be buffed out several times to look near new by someone in the biusness, where as with clear coat next thing you know you're buffing the color off of the flake making them all silver. Not having 1/8" gelcoat is part of the reason you hardly ever see stress cracks in Allisons unless they're totally abused. The last reason is that when you have a sleek looking boat, you don't need all the glitter to get attention!