I think these new weapons should be implemented too, for the sake of Realistic fights. Seriously if Zombies Apocalypse happened for real, will you want to pick something up for nasty shows ? I don't remember what the Overpower-ness of these launchers is, and lazy to look up. But I think there are some restrictions we can consider.
Here are some of my ideas :
+ Rocket/Grenade launcher can be implemented as Active gear --> restriction on the number of use.
+ The launchers have fixed Damage, which means the level of a survivor or gear stats do not effect them.
+ Rocket Launcher uses 1 rocket only, while Grenade Launchers, depends on which one, either fires 1 high-damage shell (M79 for example) or 6 low-damage ones (ICS-190 for example).
+ The launchers have long range, but they have a fixed Hit Chance of 50% on Survivors or HERCs and that means they are either get injured, or nothing happens at all.
+ I will take the range of melee weapons for easy imagination, the explosion caused by the launchers has a wide AoE of 8 or higher. 100% chance to cause knockback, either miss or not.
+ The launchers have aim time of either 0.5 or 1 second. I don't know which one it should be, but to my experience you make a survivor stand up for 0.5s in pvp and you get hit and suppressed like no tomorrow.
+ Both launchers slows you down, Rocket one decreases 15% ms while Grenade one decreases 10% ms, no matter you make the shots or not. Well, be considerate before bringing them into Island Raid tho, the penalty lasts for 3 stages.
+ Rocket/Grenade Launcher requires 3 carrier slots to carry. Now this is interesting, you guys can notice some gears with 3 carrier slots or higher do not usually have other significant stats, low damage, not impressive reload speed, bla bla. Even if there is one with both good stats and lots of carrier slots, it's is extremely rare. So your choice is, either just bringing grenades in and focus on your main weapons, or sacrificing good stats for main weapons to bring the launchers in action.
--> I said "sacrificing" sounds like a big deal, but even if you have no DPS stats u can still kill anyway lol...
+ Damage value of these 2 launchers, against Flesh and Buildings, is debatable, or not, your points.
These are just like sketches of how these Launchers could be designated in the Dead Zone. IMO everything can be implemented into the game, as long as it is cleverly designated and not to be bullshjt.
Now I just sit here and hope I did not get too many negative points of some stereotypes lol :v