I feel exactly the same way! I think the game gets easy after you infiltrate the immaculates and escape the death knights in the cave. After that part, there really wasn't a challenge in any other fights. I didn't kill the dragon in one move but it was just a matter of time where I always had it under control. Once I killed his little buddies, it felt like I was bullying the FINAL BOSS, just pounding out damage while he hit my solo tank or my summons once or twice, nothing bad because of all the elemental resistances I had for them.
The game is too stacked in the player's favor in my opinion. I finished the game in classic mode at level 22 and wish to restart in Tactician mode, but still I feel it's not going to be that major challenge, until I get the loot or the crafting.
I kinda wished that Larian would release some DLC for the first D:OS and that it would feature bosses with insane health pools and interesting skills, maybe some exclusive skills for the bosses.
The final battle was so disappointing, I mean the dragon didn't even have a special skill except for that shitty 1-2-1 shuffle.