I highly disagree with OP , for the following reasons.
The witcher 3 is beautifull game , but i don't play it to be lost within in. Yes you're following a path , but the thing the game ask you is not to find something but what you , the player wants to do once you've reached your destination. I had fun playing as geralt because i took decisions , not because i found a clue about some monster / event. The quest design was fine because the goal was to present the player alternative on how you deal with certain situation and you had plenty.
Watching the rest of the game on youtube is forsaking your adventure of playing as geralt , of making your own decision within that world , i wouldn't recommand it.
As for the combat , quen is not the only available option and i'm a quen player . If i wanted to do something else i had other deadlier options and that's not even counting the stuff the expansion added , instead of defending , why not use a crowd control sign ? or you could control your ennemies with the agni ? The combat becomes trivial if you exploit something ? but that's the intended purpose ?!