It's not ridiculous at all, especially when the only viable option for a Nightstalker grenade is the smoke. It's a "SMOKE" grenade, it's meant to block field of view. If you don't get slowed down in it then you'd be able to easily run away from it and then smoke would be useless. It's suppose to give NS an edge. Think logically, bungie will never fix something with that logic, especially when it isn't broken.