That's not an argument, plenty of commanders are situational. When was the last time you saw Jaeger Armor being used in a 1v1 tournament? Feuersturm is amazing for the urban 3v3 and 4v4 maps.
On its own it is not. I used in a combination of arguments. When it comes to commander design, I have no problem with commander that have great abilities if the rest of the abilities are UP. My point is simply if the barrage was part of Grand offensive it would even mention being nerfed.
Currently is available is situational commander with situational abilities like:
MP40 and Hezter.
The ability itself need to many prerequisite like going T1 and building a Leig. Else it completely useless.
And my suggestion aims to fix that. So I do not see the problem.
One could simply bundle it up with flamer scrap m40 and add a new ability or one could allow Leig to built from HQ so that it does not force T1 or one could add the GW 34 mortar with incendiary barrage which is in game so that ability has some use even if one goes for T2.
I have yet to see a single argument why that would be bad for the Commander or the Game.
In you opinion the commander is great but that does not meal that adding a GW 34 with incendiary barrage would make it broken.