My personal theory is that a lot of the love for The Witcher 3 in particular stems from the fact that very early on it has a sex scene with full nudity, with a female character who is supernaturally hot according to the lore. There's several women Geralt can seduce, and I suspect a lot of people who mostly play hentai games were in shock to play something with more exciting gameplay than match-3 grids or a jigsaw puzzle.
The Witcher 3 doesn't seem like a bad game, but I'm similar to you in that I've bounced off it a couple times after a few hours. There's nothing particularly bad about it, but nothing that really grabbed me and made me want to keep playing more either. I still plan on giving it another shot eventually.