Card value reflects current singles market.
With the rise of tribal decks, which were comprised of many 1/1 weenies to be boosted later in the game by Kings, Lords and Enchantments, Mishras Factory was a great first turn play
For example, if Clive's Hideaway's hideaway ability is copied and two cards are exiled, you may cast both exiled cards without paying their mana costs (assuming you control four or more legendary creatures at that time.) Gogo's ability can copy any activated or triggered ability on the stack, not just one with targets
White weenie decks don't really have a use for all that extra mana should they fail to Armageddon, so trading two mana for one more point of damage each turn stands as a pretty fair bargain
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It wont stop someone else from taking your creature with a different mind control later since these effects usually overwrite previous ones (something about timestamps)