I also miss the old plasma cannon. Although the new one is arguably better, more efficient, more reliable, safer. But firing what is basically a heavy pulse laser doesn't quite have the panache of the space BFG of old.
One of my most vivid Starsector memory was the first time i encountered a quad Plasma cannon Paragon. It was with Dynasector since variant randomisation wasn't a thing yet. I was used to bully standard Paragons variants with an Onslaught. And that day, i faced it, with its four big guns, slowly turning to face me.
"I think i should be able to take it, i'll go close to it and... Yeah, yeah, nope, no, definitely not! Change of tactics! Oh @$%& this isn't going as planned!"
It's not often when getting fired upon by a gun was a cathartic as firing it. Despite my nostalgia for the old BFG, i'm pretty okay if the new one stay. Moreover, if i'm really craving for something big, expensive, unwieldy that shoot death, some mods added their own plasma cannon variants that also scratch that same itch.