I feel like there is a real discrepancy between the ease with which rerolls on attack dice are available compared to rerolls on defense dice. Target Locks provided easy attack rerolls and there are various upgrades available to make them even more plentiful (FCS, Weapons Engineer, various pilots). There is also Predator which is one of the most popular EPTs.
Defensive rerolls are much harder to come by. Lone Wolf allows 1 dice to be rerolled but only if you keep away from your buddies. Rey will allow rerolls but only in arc. There may be one or two others I have forgotten but they are certainly not common.
When X-wing was introduced, this made perfect sense. Ships could only attack once per round so the rerolls from TL were self-limiting. A ship could be attacked multiple times in a round which would exaggerate the benefits of defensive rerolls.
Recent Waves have changed that though with plenty of ships able to attack multiple times per turn which boost the value of rerolling attack dice. /D Defenders, Dengar and Resistance Chewie all spring to mind as examples of ships that can make multiple attacks. I think it is time FFG started to provide a few more upgrades that allowed defensive rerolls.
This is especially true on low agility ships (I don't think anyone wants to see Soontir made even harder to kill). Maybe an Evasive EPT that allows defensive rerolls as an Action?