May increase perks increase my the tiniest fraction of a percentage. Due to this and the likelihood that fraction is rounded down, it keeps it as one. Add to that: all rocket launchers have a single shot. If one-- especially one like the Coil-- had more than one, it would be immediately overpowered. Literally twice the mag size [i]and[/i] a multitude of mini rockets?

It's most perks on exotics that doesn't really work or it's so small and insignificant that the difference is hardly noticed. For a example the Gravitation Forfeit is supposed to increase invisibility but only does it by 1.5 to 2 seconds. they've removed the secondary perks from a lot of the returning exotics. with a few exceptions exotics or completely underwhelming and not worth using, at least until they fix them and not just buffing them but bringing the original secondary perks, like extra grenades.