The thing with the "definitive" edition is that the marketing guys would love us to just accept that this is the PC version plus a load more but in fact it's actually the PS360 version plus a load more and that's also what the PC version is. The PC version and definitive edition are both enhanced versions of the PS360 version but both have taken different routes in that enhancement.
They both have 1080p and TressFX and the definitive version also has "a new particle system, new lighting work and enhanced shadow-casters, tons of more visual storytelling elements (more debris, more details on walls, more density in the environment for vegetation) and upgraded characters (new face model and body textures for Lara)."
That's all great but when you look in the options menu of the PC version is also has "ultra" options (which one has to assume in 2013 is beyond the PS360 settings) for textures, shadows, level of (world) detail, depth of field and SSAO. It also has extra checkboxes for tessellation (which we know is even lacking in the definitive edition), post processing and high precision.
So it's reasonable to assume that many of the enhancements in the definitive edition are already in the PC version, perhaps in a different implementation, and that both version have effects that the other lacks. Don't get me wrong, there are some impressive things in the definitive edition that are definitely beyond the PC version and I expect on balance and in 2D mode the definitive edition is still the better one - but it's not a super-sample of the PC version and the differences may not be as great as is made out in some of the write ups.
I expect that's why we won't see these new effects patched into the PC version. They're likely incompatible (and in some cases inferior) to the changes already made for the PC version.
