Not sure why you keep mentioning his 23m release clause that was then, 23m is a LOT of money for a player such as Fellaini, 12m is not.
We paid 15m for him and he scored 33 goals, mostly from midfield, he was at times unplayable, at times lazy and disinterested, he was a top, top player for us, not perfect, but certainly not as bad as your trying to imply, I realise you have a different viewpoint of the player, a different viewpoint than probably around 90% of Everton fans, who thought Fellaini was a good player for us, thats fine, you are entitled to that viewpoint, personally I think your wrong.
As for now, 12m is buttons for a player of his quality and if we had an unlimited transfer kitty I would snatch him up tomorrow, but sadly we have a limited transfer kitty and a "luxury" player such as Fellaini is not on our shopping list.