The monsters with the unique names are defeated in the same way as their regular counter parts. For example, During the Jenny O' the Woods quest the dialogues build her up to be a hate-filled ghost lady. However, she was defeated with the same strategy I use for all other specters in the game.
I also question why people went ape-shit over gwent. I was never a fan of card games, and that solidified by disbelief even more. This is like if you were going crazy over tennis in GTA 5.
The mutagen system is a nice idea, but I never found myself using green or yellow mutagens. Red and Blue were enough to decimate any monsters.
Lastly, I found weapons and armor repairs to be very annoying. It was just like in Fallout 3 and oblivion; I understand it's part of the immersion, but this feature just slowed down the game.