3 to 4 decks could play Yogg (Tempo Mage, Combo Druid and Control Warrior, even some Rogue decks) and 3 decks/classes can play Kazakus. A lot of these decks could get by using a handful of spells and still play Yogg, in fact having too many spells wasn't that great with Yogg due to backfire potential on empty board. So deck restriction isn't that different and in new rotation having a deck made around Kazakus will sting even more without Brann and Reno.well, kazakus is like a stronger, far more consistent and flexbile old yogg honestly, somehow people don't get mad at this one because it's less RNG I guess. Yogg actually was more restrict with deck building and play style, you had to play lots of spells for it to do anything, kazakus condition is actually easier and faster to meet.
Kazakus is more consistent and faster yes but Yogg has bigger comeback and swing potential. More difficult to play around too. There are a lot of boards where Kazakus can never win but Yogg can turn any situation.
This is talking about the OG Yogg of course. The game was heading in a direction where a lot more decks started to use Yogg with just a few more spells thrown in. Kazakus has a hard limit of 3 classes AND highlander control decks. Yogg was definitely a problematic card that needed the nerf, Kazakus is about to be a crap ton weaker with the rotation.