IMO adding additional traits to the total is only a pain for math, obviously more so for NPC's for Narrators etc. On the PC side it only truly matters when overbids come into play as a PC which already outmatches another PC will not "more outmatch" a PC. you still win on RPS 1/3 or the time, you still retest abilities the same.
Trait totals would be equal most of the time for similar characters, most people forget their form traits, or their weapon traits, or bonus traits for talens, or traits for a pack tactic, or traits for a totem, or traits for a gift, or traits for cover, or traits for minor rites, or traits for blah blah blah... so in the end +3-5 traits against an untrained combatant really doesn't throw off a curve for anyone other than those people who care about the minutiae and are looking to stay on the top bleeding edge of traits.
Those folks are in this game based on my experience the very very few of which I am one and know of very few others. Besides, anything which encourages people to remember to bid negative traits against people to get them to lose traits faster out of necessity I am all for...