GPU hardware hasn't supported 3-component texture formats for a long time (aside from packed formats like DXT1).
I'm excited about ARB_Sparse_Texture, though I'm a little confused as to why they don't support any of the 3-component texture formats.
If you ask GL to give you an RGB texture, on the GPU it will allocate an RGBA texture and pretend that the alpha channel doesn't exit...
Yeah that's something that I always have a whinge about, so this makes me very happy
I think the biggest improvement is the conformace test. From what i head from who prefer DX over GL is that the drivers sometimes have different behaviours for different cards (with openGL). With this change, all the driver will(?should?) have the same behaviour, making it easier to develop openGL programs.
[the ARB] has created the first set of formal OpenGL conformance tests since OpenGL 2.0 [and] full certification is mandatory for OpenGL 4.4 and onwards