Alexine wrote...
Maybe they should have given Jacob a defense-stripping power (Warp/Overload) than his ammo power (Grunt takes care of that)
I don't think every squadmate needs a defense stripping power though. Jacob is useful regardless, though obviously different classes will get different results. Let's discuss his two greatest strengths.
1)
Pull: Jacob has the earliest access to Pull out of anyone in the game. Not even Adept Shepard can get Pull without a prerequisite. Pull is great at starting Biotic combos for Shepard or other squadmates to finish. It also kills undefended husks instantly. Finally, when evolved to hit an area, it can be quite useful for briefly staggering groups of defended foes in an emergency on a higher difficulty level. Even a moment of staggering can give Shepard the time he or she needs to get into cover. Jacob might not be able to use Pull as often as a high level Samara/Morinth or Jack, but those squadmates have prerequisites for their Pull, often preventing them from mastering a desired set of skills.
2)
Incendiary Ammo: Although Jacob's ammo power might seem less useful on combat classes with their own ammo powers, keep in mind that many combat class builds focus on developing their ammo powers after mastering their class skill and passive. Most Vanguards want to master Charge and their passive skill before focusing on Incendiary Ammo. Jacob's Incendiary Ammo can be a stepping stone to your own ammo powers if you choose the squad form. Or, if your class doesn't have any ammo powers and you chose not to use a bonus power for that role, Jacob has you covered. And it's not only useful against armored foes. Aside from stopping regeneration, Incendiary Ammo can trigger panic in organic foes, effectively shutting them down and protecting the team.