I don't see the place where you think D&D RPGs suddenly "got it wrong".
AD&Ds rules were more arcane than anything the 3rd edition games could come up with, the only thing different was that there were options for multiclassing and min-max-based character building in the 3rd Edition games, just as in the pen-and-paper rules.
However, the key word here is OPTION. In that you could choose to take it, or not.
You didn't have to use them. Any of the neverwinter nights games were easy enough with any single-classed character. If you didn't want it to be, it was not a numbers game.
Also consider that both NWN and NWN2 have much heavier multiplayer focus than any of their predecessors, which means providing a whole bunch of rules and options that might not have made a lot of sense in the main campaign. That means, yes, adding in the option of playing a Svirfneblin Arcane Scholar of Candlekeep. Prestige classes, multi-classing, min-maxing, all of that, because players running their own campaigns constructed with the tools would want it.
All this reads like is that you don't like building a character. Fair enough. But wait! There's a "recommended" option for every single level in any class as you go through the campaign! And it worked! Why didn't you pick that option rather than fault the games themselves?
I for one consider Mask of the Betrayer one of the finest D&D RPG stories since Planescape Torment. I can't fault you for "throwing your hands up" because you thought crunching some numbers (even when you didn't really have to) was too hard, but frankly speaking, you didn't give it a chance.
