My opinion as someone who played 200+ hours of Warband which is quite a bit but I know for some it's nothing, I always played with auto block and going to directional blocking here was jarring. I think the skill floor for defense in this game is higher than most, though using a shield definitely helps alleviate that. At the same time, actually getting the blocking down is immensely satisfying and the improved animations and everything going on was incredibly fun. I think it'd be cool to tie auto blocking to specific difficulty levels, it should definitely be an option in single player because you want people to enjoy the game.
Even if you practice enough to be great without a shield, you will get sniped by archer units without something to protect you. The balance is way off regardless. I COULD become accustomed to no auto-block, but is it worth it? My save file will corrupt itself and the entire map will get snowballed, or my character will die of old age and all my progress lost. Not to be a debbie downer but I've decided not to play this game for now. It wasn't what I expected given the price and really I would be pleasantly surprised if the game ends up having the same longevity that warband had.