I never said you abused anything. Actually, I expected more powerful characters like Therron. Many characters had neither exceptional offense, defense, or trickness. I don't mean to be rude, but I'd be worried that a character like Tobias would be a liability in a normal 15th level group. In death match against powerful characters, well too bad.
Well, since I knew Therron was using different constraints during the game, when it actually mattered, and didn't find out about a Nimblewright or bad wildshaping until after the fact,use of Oriental Adventures stuck out. But, considering Norman's current design, and other things Dr. Midnight has posted (in his story hour, for example), it might be fair to consider his extra ECL a handicap. Even with several "extra levels," I still don't poor Norm would stand much of chance against Therron, Dabbil, and other top characters in a 1 v 1 battle. Finally, for fighting type characters, equipment seems to have a bigger impact after a certain point than additional levels. For example, after a certain point, the benefits of being a half dragon outweigh the loss of levels for a melee character. Often at high levels, it seems that penalizing equipment is a better balancing method than penalizing levels. What does equipment give a fighter? Stat bonuses, better AC, magic weapons, special defenses, movement, and magical attacks. What does a half celestial give a character: stat bonuses, movement, better AC, special defenses, and some magical abilities. The template's abilities are more comparable to an array of items than to class levels. So the loss of 150k GP may be worth several extra character levels.
While fun, NWN wouldn't really work for running a THIRD EDITION game. It makes a number of rules changes that have a huge impact on the game. Casters can't use the cast defensively option. Trip and Disarm work differently. Fine tuned tactical movement is almost impossible. Characters often incure AoOs for no real reason. The stacking rules don't work. Also, changing your action after a certain point seems to kill the rest of your round as well. It just doesn't seem very tactical.
Finally, I think an optimized one round kill character is unfun for GoD. Just as you didn't seem to have much fun after Therron was Mazed before you could do anything, a player whose character took a 500 point shield bash attack before doing anything probably wouldn't have much fun either. If you're killing someone slowly, then they can keep playing and decide use other strategies, run away, etc. In the end, they could still die, but they get to play the game while dying. Of course, good strategies are hard to argue with.
