They should have rotated Yogg into wild. It's not
that powerful there. Or they could have capped it at a more reasonable number of spells. Say 8? There were ways to go about it that didn't kill the card, but Blizzard always nukes the really unpopular ones form orbit to make sure they see zero competitive play, which any reasonable nerf would have done. And they refuse to do bans because they want ladder to be exactly like tournaments.
Yogg was a problem in competitive, but part of the problem is that competitive isn't set up that well anyways. But it's the reason Druid is neck and neck for most played tourney class with Shaman (which is more op). It leads to massaging win-rates to be more uniform across the board and makes it much harder for the better players to consistently perform. Which is something people really really want in the competitive scene right now. It's really exciting for people to watch tourneys where player X has been around for a long time and some underdog is up against them. It's not as fun to watch a tourney of no-names, and the tourney scene has been really suffering as of late because of this, whereas something like Batstone did massively well.
The added "problem" is what you stated. The perception of Yogg is a massive issue. It has the largest rng spread in the game, and it almost always is the last thing to happen in the game. This has led to it being one of the most hated cards in the game, because people really really do not like massive rng events that happen
at the end of the game. Something like
Animal Companion by comparison is something we don't care about as much because the spread isn't very big and it happens in the middle of the game, so the difference in effects isn't as massive as often and it's not usually the last thing played that game.
TLDR: Yogg makes it harder to people to be consistent in tourneys and is the big rng event that happens at the end of the game, so it was bad for the reputation of Hearthstone.