Q:
Mandatory Major Trait
A:
There are reasons not to take them but generally it’s a pretty big tradeoff. You’d be losing 30% critical damage and a ton of healing, and there’s not really a whole lot else in the other trait lines to compensate.
I’m not sure about “the best s/he can be”, since I don’t have a dedicated sPvP team and can only play free tournaments, but I play a Shout build that has neither of those traits and I’m still very, very effective.
The thing to remember here is that defensive Guardians are (as Eveningstar describes it) are “meta-good”, which means you’ll see a of Guardians that spec in deep Valor (Yeah, Toughness!) so it would be silly not to take those traits.
I would almost say Monk’s Focus and Altruistic Healing is mandatory for most defensive builds simply because they’re amazing.