Because they have automatically slower firing shots and and are less powerful (expect with very accurate charged shots and follow ups, though this takes a lot of time and reduces dps compared to pulsar etc)
Maybe think about giving both catalyzers 4x shots at a time instead of 3..
Also remember that you can edit your post instead of posting another one, especially when noone replied between your two posts.
The biggest complaints right now are that it takes too long to build charges, charges just poof when the target gets offed by other party members, and charges not dealing enough damage. The last complaint is really a reflection of the first two; the charge detonations deal respectable damage, but take too long to set up and are often wasted. With that in mind, I propose these two changes:
1) Charges detonate upon expiration as well as death of target. This causes them to damage all other enemies in the area when a target dies, or allows for detonation without the hassle of trying to land a normal hit. The normal attack might need to be nerfed slightly in compensation.
2) Widen the blast radius, or at least the chain-reaction radius. When I first heard of the Catalyzer, I envisioned loading a bunch of enemies with charges, setting one off and having the whole area light up. The chain-reaction radius is currently much too small; it is next to impossible to chain detonations.
I had a catalyzer-improvement post here.
Basically:
-Increase chaining radius (like Mohandar also suggested)
-Let charges stick to enemies even if they hit a shield (but still require to be next to a weak spot to do damage when exploding)
Now instead of a gun that's fiddly to use against groups of gremlins, you have a gun that's AWESOME to use against groups of gremlins.
Also remember catalyzers require a end boss earnt weapon (the base catalyzer) so they should be more effective in general compared to weapons that dont require that investment in time.
Maybe also think about giving the industrial catalyzer a random status application on charged shot detonations.