Ymmv but I don't find either the brain-poisoning or the moron-selection ideas very plausible and there is no fluff-support for either.
Currently WH40K has Ogryns in a comic-relief 'Dumb as Rocks' role. Obviously a GM can change that in his game - but some players will not like this.
As I said, I think the only hope is that GW see a marketing opportunity in opening up Ogre Kingdoms models to WH40K armies (with conversion kits too). This would require a canon shift - which GW would do if they saw money in it. As a player of the TT WH40K game, I can imagine expanding the IG range for Ogryns and even a Feral Ogyrn ally list as a concept that has potential.
N.B. Ogre Kingdoms still has Ogres as comic of course - just in more than a 'one-note' way.