Transparent materials don't look that good.

I can tell of two issues (which are related to each other I think):

  1. Transparent surfaces can not be 100% opaque. Even if it set to black, there is still leaking on surfaces that are behind it. It is supper annoying especially for decals and when I tried to make some foliage using transparency.
  2. This leads to sorting issues. Since there can not be 100% opaque translucent surface, when you stack some of them one after another it all melds into chunk of mess.