It wasn't just the Alien Blasters. They changed the appearance in the v1.4 graphical revamp. That was when bobble head mage was removed, helm appearances were added, and so on. Tons of item designs changed (wammos, warlord, jeweled bows), most of which were for the worse. They did the revamp to make the game look "newer" and more "polished." As to why they changed Alien Blasters specifically so much, it's anyone's guess.
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