First and foremost, this is not to insult either type of player.
The Casual player is the core of all game's, they rarely exploit or abuse a game's content. But, they do tend to have big problems with harder than normal content, and thus complain. ESO has already made the mistake of making some boss mobs way to easy to kill. They have to go to another site to figure out how to make it thru that boss and in all case's to get thru a public dungeon.
Hardcore is exactly the opposite, so the derv's have to figure out how they did it and somehow fix that to, they rarely have trouble with any game content and fly thru the lvl's in amazing time.
Unfortunately, game's seem to cater to the Hardcore and this is were a game start's playing catchup. When this happens its hard to turn it around.
Example, VR level's. Were they needed? Probably. Were they designed well or did it seem like they were thrown together?
Even though the game is amazing and fun.
Question, how long does it take the Hardcore to finish a new console game, before he's won? Not long, right. So here is the problem.
Dev's want everyone to love the game for the longest time possible, which is not very realistic.
I would say fix the major bugs, kill the gold sellers and buyers, forever ban the exploiters and abuser's.
Your casual player will stay for the longest amount of time and bring in fresh players.
The hardcore folks will (win) the game at light speed and move on, they are going to anyway, they are a small percentage of the population and won't effect much of anything when they leave, its normal to all game's.