As I feared, no Larian developers have shown up in this thread.
This is a topic one could write books about and its not clear to me who would even want to read them.
I'll just give other examples of what I think was a really bad design:
Dragon Age: Origins.
So Bioware had done the epic Baldurs Gate 1+2 and then they figured they would make their own rulesystem. It was bad. Really bad.
There are three classes. You have four subclasses, but in the main game you get TWO of them, and in the expansion everyone gets all four, and anyway they each consists of just four abilities.
Furthermore both warrior and rogue have two groups of abilities. Warrior for shield and twohanded weapon, and rogue for ranged or two weapon figthing. Obviously you would pick either of these styles and exclusively only skill those until you have them all, so there is exactly two ways to play either class.
The only class that actually got any sort of choices is mage. Even with mage I didnt like that I had to pick up spells I didnt want to get spells I wanted to use.
The design of skills was really bad too. You had far too few levels so making an allrounder thief was impossible.
Of course during the development of DA:O Bioware was also sold to EA, who instantly made the game much worse - removed the multiplayer, added a port to consoles which screwed up the interface on PC, made parts of the game a download for which you had to give up all your personal data.
By the way, its a general tendency in fantasy games that the spellcasters are much more interesting than the warriors. In part of course also because those who play warriors want a simpler class to begin with.
