There is virtually no reason to actually retain incendiaries and molotovs in co-op. On the flip side, there's a lot of reasons to be rid of them.
The laser guided molotovs from bots, which seems to have made a return in this patch just make the deaths feel random, unfair and arbitrary. This is exacerbated by the new CQB maps, where the molotovs are even more effective.
They enable rushing behaviour and aren't all that useful to players outsode such rushing. The incendiaries are good for one thing for players, and that is rushing and blowing up caches; they allow rushers to simply sprint up to the cache and blow it up by simply getting that one grenade on it. This sort of behavior makes the game worse for every other player and ruins the pacing of the game by making things like teamwork and coordination (required for the point, since you either have to escort the demolitions to it or cover the guy laying down a explosives) pointless. This sort of behaviour can even get toxic, where rushers will blindly throw incendiaries which wind up hurting their own team.
They are also mostly worthless in blocking areas; bots simply rush through them and all they do is block players' line of sight and constrain their movement.
They pretty much turn frenzy into a joke; you don't die to anything so much as you die to the molotovs, and it's the same story every single map and every single point, where the team drowns in molotovs and doesn't even get to see any of the actual rushers. The molotovs also make little sense in the context of the game mode, since they essentially provide powerful AoE ranged attacks to the melee bots; thus breaking the whole theme of the mode.
Each of these issues has been exacerbated by the new patch, which has seem laser guided molotovs return in a big way.
I think that it's time to admit that the incendiaries just make co-op worse overall and make them a PvP only thing. The only real beneficiaries on the incendiaries in co-op are the bots and rushers, who gain at the expense of all other players.