They are. You have to engage carefully at first.

I would recommend having fully upgraded Iron gear before even stepping foot into the plains. Even then. Do so cautiously. Use ranged attacks. Stay as well fed as your supplies allow. Even the swamps just got kicked up a few notches... I think they're going the way of the "souls" games. So if that's not your thing and you're a casual like me, maybe post your issue, or consider a different pass-time.

For the plains. Have plenty of Medium Health Potions, have some stamina potions, and definitely make sure you're bringing your best arrows. Anything less than obsidian is just gonna flop...