tomimt: Might I ask why? It's not like the GOTY owners are going to get anything the owners of original game and the DLC packs don't already have.
A small number of owners of Witcher 3 original release want the GOTY version because while it is 100% identical as a game and content, it comes with a single EXE installer that installs everything in one shot, whereas the original game is now one EXE file, the free DLC is one EXE file, each expansion is one EXE file, and if there are patches for each, then it becomes 8 or 12 or more EXEs to run to install the game and all of its expansions and DLCs.
This is such a huge problem to do 1-5 or whatever times over the lifespan of owning the game that it apparently completely destroys the entire game experience rendering it completely shitty, and the company shitty for taking everyone's money and not giving them the free GOTY version too.
To be clear, that's not my own personal feelings, I'm pretty happy with what I have already. I'm just answering your question roughly summarizing the collective feelings of everyone angry at CDPR and GOG for not getting a free GOTY upgrade based on personal observation here in the forums (and without judgment either way).
A single installer would be nice to have but MeNoGivvaCrap, the game is awesome and I feel like I owe them money because I ripped them off not paying more for it. :)