I think just an across the board +5 points for large base ships wouldn't be out of the question, as the only one I can really think of that's truly mediocre is the Firespray. This would manage to put the hurt on both of the top meta lists, Jumpmasters and Palpshuttles both, and keep some of the old hatreds on a lower burner, such as Fat Hans and Donut Dashes, and give a bit of a kick to things like Brobots to boot.
[snipped: Counterpoints LOL]
In a game where small ships are harder to hit, easier to maneuver and don't have lower damage output
your proposal is 100% worthless.
100% worthless? Probably not. Not even Trump is that bad, arguably.
I'll admit it's probably too much a hike in increase, but with all the problems you state, each of the current big lists that show up more often than not, do tend to run a shuttle, brobots, or a jumpmaster. Alternatively, the ex king people speak of with fear, was a fat han. Maybe this particular fix is a bit out of date, and +5 is probably a bit high.
Point cost seems to be the general, over-arcing method of attempting to balance things, and a lot of arguments that come up, tend to be that something is too pricey (x-wings), or too cheap (jumpmasters) and that was what I was looking at for a 'simple' fix. Or at least, break things in one direction and go from there.
But just to throw a little hyperbole back in the mix, We'll just say your 100% wrong is 100% right, and nothing needs to be balanced at all.