Hello!
Yes, we nerfed down on the free grenade feats a bit in order to keep grenade within the “scarce resource” area of balance. The intent was to still provide some extra grenades during a mission but keep the grenade pickups relevant.
The talent should get some updated texts shortly that should state clearly that there is a 5% chance for you and all allies in coherency to gain a grenade whenever you or any ally in coherency kill an elite.
Thank you for the feedback! We will keep track of how the trait fairs and balance accordingly, either increasing the chance for grenade gain or simply spawning more elites to increase your odds.