I don't want to get into one more argument which will probably end up in a battle, as most arguments do. I just want to point out two fundamental problems we have here.
1) Terms like "balance problems" and "broken systems" really depend on perspective. There is no definition of "perfect balance", as everyone prefers a different balance. There is no a commonly accepted standard of what a good balance is, and as such "balance problems" out of context doesn't have much meaning. And in context, it is confusing, since everyone has a different context they argue from.
In other words, what one player may dislike about the balance, another may like, and vise versa. Talking about some objective problems doesn't make much sense.
2) Facts are cunning beasts. It is always possible to handpick some video illustrating one's point and say, "This proves I am right". Another person then may handpick another video, illustrating the opposite scenario. To make a linked video into a relevant argument, one must prove that this video shows regular scenario, not a, extreme deviation from the norm. For example, in our disagreement on the balance of warrior vs mage in NWN games, you can link a video of your Sorcerer slaughtering entire room of enemies with a couple of AOE spells. I then can link a video of me dying to a single melee warrior in arena in Mysteries of Westgate (although it is NWN2, similar balance notes apply), since he hits so hard, my Wizard fails all concentration checks and can't cast a single spell before dying in 5 seconds. Both are scenarios that occur in games, and both support our arguments. However, you say that the first scenario proves that mages in NWN are strong, while I say that the latter scenario occuring in my games makes me dislike the way mages are implemented in NWN. Both claims are reasonable, and it is a matter of taste of what is important for you. For me, the second scenario happening from time to time is too annoying for the first scenario also happening to redeem it.
Ultimately, all these arguments are reduced to what is important for the player, or, specifically, what they like/dislike about the game. I liked DAO combat way more than, pretty much, any other Bioware/Obsidian team-based combat (I liked Mass Effect 2/3 combat even more, but that is a different beast entirely), and if there were balance specifics I disliked, they were not significant enough for me to like the combat less. I played all major classes in DAO for my protagonist (mage healer, DPS mage, warrior-tank, rogue-archer, DW rogue), and I didn't notice any of them to be particularly harder or easier to play in any scenarios. While in NWN games some battles really made me wish I was a different class. Morag battle as Arcane Archer with Daelan in my group probably killed half cells in my body, while for a well built Wizard or Sorcerer it is a cakewalk. Oppositely, fighting Desther as Wizard/Sorcerer must be a huge pain, while my Fighter didn't have much trouble there.
