You could have just made Kylo Ren the big bad on his own, easily. I was only ever interested in anything about Snoke insofar as it relates to Kylo Ren, anyway, which is why the decision to have Kylo supplant him was the right one. If you want to give him redemption, that's not precluded by him being the central villain, and if you dont, he's rather violently rejected the possibility twice now.