ZkinandBonez said:
The reasons for why half the galaxy remains unexplored may be convoluted, but it’s not illogical.
It’s just another over-the-top EU explanation of things, as evidenced by the fact that there was never any kind of map until about fifteen years ago. There wasn’t even that much of a demand for it until then. From what I’ve gathered from the wiki, most of this has to do with the lore of The Knights of the Old Republic games.
The first time I ever remember seeing any kind of map was in Vector Prime, which makes sense given that the boundaries of the galaxy mattered much more in the NJO than they ever had previously. Really, though, there’s enough old stuff before that about the Chiss Ascendency operating in the Unknown Regions in The Hand of Thrawn that I’d have probably speculated about them rather than the Rakata if it weren’t for Rakata Prime being on the new map.