No one has yet replied justifying this massive overlap of Mind Flayer and Parasite.
Here I agree. The mechanic is new but it doesn't bring anything. Why would you give your opponent the opportunity lobotomise your creatures? Moreover, mind flayer, liquid shadow and lobotomiser already do it better / faster / stronger / cheaper (
) (as would Daft Punk say).
You should think of a second transformation which would give a higher interest to the card. The target creature becomes (a) undead (this way you would have a nice interaction with rewind and the like), (b) a death card (this way you would have an interest to play eclipse with it, (c) poisoned (not only will is it loboed but it will die after a while), (d) poisonous if ingested (meh) or (e) something unexpected and epic.