If they're walking, they're not really turrets are they?
In 1.2, the best passive damage-mitigation tactic is to make sure you have the bonus from Bulwark every turn (i.e. stand still and fire), whether you were in cover or in an open field. If you absolutely had to move you'd jump and brace or used Vigilance so as to not lose Bulwark. The way Bulwark works in 1.2 gives you a strong incentive
not to move (because you lose Bulwark if you do).
In 1.3, the changes to Bulwark means the incentive not to move is removed: As long as you're sticking to cover, you'll get the benefits of Bulwark. You can no longer turret in the middle of an open field like you can in 1.2. Also, the mitigation from cover is reduced by 5% (down to 20%), so it is vitally important to either have lots of evasion pips or Bulwark to get that reduction up to 40% (down 10% from 1.2). If you brace or use Vigilance in cover, you'll max out your passive damage mitigation at 60% -
20% less than in 1.2 10% more than in 1.2 (thank you
@Antagonist85 for the correction).
This means that Bulwark is no longer the no-brainer choice it is in 1.2, and since you're free to move why not pick up Sure Footing to gain an extra evasion pip?
The meta is very likely to be Bulwark + Sure Footing + (Ace Pilot/Coolant Vent), which in and of itself leads to the 1.2 tendency for static trench warfare being removed; the new Bulwark gives its bonuses just by being in cover, and Sure Footing gives an extra pip anytime you move. So why not move? Moving from cover to cover only increases your defenses by giving you some evasion pips in addition to the damage mitigation from Bulwark.