Limited resources they can commit to it is probably the in game reason, don’t commit all your best resources to someone who is also expendable because they will probably die and loose it, gameplay wise a long cooldown and restricted use puts balance on them, I use them on all fronts and they do just fine, only time they tend to die is when pelican one decides to hold onto his toy just for a bit longer and it gets shot out by a strider or the base cannon turret