Before you read any further: I don't have any insight knowledge whatsoever. The only thing I know (or at least what I believe) stems from various discussions on the forums and information provided by the mods.
I find this VERY hard to believe, especially when all I get when I search for "WOTC pokemon rights" is info on how long they had the license for and what happened when TPCi took the distribution rights back after WOTC's license ended.
Funny, the first thing I found were the lawsuits from WotC against TPCI. That lawsuit got resolved as “the parties had entered into settlement” and quite frankly the whole thing wasn't entirely connected to distribution rights, but still.
So far, every time the topic of Gen 1 popped up on the forums we eventually settled on the issue of licensing rights (among over things obviously). I don't find it hard to believe that back in the days, when no one knew how big this franchise would become, someone struck a deal with WotC that would give them enough leverage to prevent any kind f 1-1 reprint of the base set (and with the current rules it wouldn't be fun anyway – it's not Gen 1 if you can't chain 4 Computer Search, 4 Item Finder, 4 Bill and 4 Oak in a single turn).
The shadows of the abyss are like the petals of a monstrous flower that shall blossom within the skull and expand the mind beyond what any man can bear, but whether it decays under the earth or above on green fields, or out to sea or in the very air, all shall come to revelation, and to revel, in the knowledge of the strangling fruit - and the hand of the sinner shall rejoice, for there is no sin in shadow or in light that the seeds of the dead cannot forgive...