That was done in 3.0. And GLSL 1.50 didn't get rid of "uniform". And "inout" is not usable on variables, only on argument lists.3.3 allows the shaders to use in/inout/out instead of attribute/varying/uniform keywords
ES 2.0 uses attribute and varying. It doesn't allow for in/out.which is exactly what we need for OpenGL ES 2.0.