I could see it working on an alpha strike setup for a phase ship. Outfitting them with something like AM blasters, Heavy Blasters or Phase Lances and given that you will naturally run up your flux from phasing anyways, you could pop out and strike someone for alot of damage. But yeah with how wildly your flux goes in any given fight and losing the flux war is not ideal, its not something thats applicable everywhere.
Oh yeah, it's not useless. Phase ships can make decent use of it if you overflux their weapons because soft flux doesn't interfere with their defensive system. Some shielded ships like the tempest can also squeeze some value out of it, it's just super niche and even at its best provides an average damage bonus of like 10 percent.
Maybe 15 if you get lucky, but then you run the risk of getting blown out. I still take it on those rare builds that can use it: damage is damage after all and the elite bonus is pretty nice.
Overall though, it's pretty sad when ballistic mastery is so broadly useful.
Another possible "fix" for EWM is make it start at a 10% damage bonus and scale up to 30% at maximum flux. This would guarantee you're always getting at least 10% bonus damage, except that it actually doesn't because you still need to be within 600 range of the target. EWM has a very high ceiling for its bonus at 30% damage, but the reality is you're going to spend most the time near the floor because it scales on range and flux at the same time. Adding a respectable floor to the flux scaling would nice considering BM gives you 10% damage and range all the time no matter what.
Actually, now that I think about it, I'm gonna make a post in suggestions...