I don't think they could've gotten the licence's by buying LUG, the contracts were between the owners and LUG, not WotC.
The reason for buying out LUG seems to have been simple, they did it becasue they could. LUG was (I'm told) very over extended financially, making them ripe for a buyout. There's no way WotC could pull that off with any of the more established companies, so LUG is a victim of "Vulture Capitalism"
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