Normal Frag Grenades are pretty terrible unless you go to explosive build in T5 because they do nanoscopic damage due to how the game is balanced.
Instead, add Utility style Smoke Grenade which would be useful always in higher difficulties.
You are pinned down, pop smoke in front - which causes the enemy to lose focus and take pot shots. Allowing you to run for better cover.
By allowing the player a 3rd option
Frag \ Specialization \ or smoke
It gives players more choice and more tactical use.
Because some grenades like Frag is pretty useless.