[Ack]

It will take 4 times as many shots to destroy a ship (at least). This means you have more rounds for the shields to regenerate. Of course, doubling their regen rates would be good too.

And as a consquence combat will have to be adjusted to 120 rounds max vs 30 for any meaningful result. And then there is an issue with supply usage per shot and for movement. Essentially you'll end up with longer combat sequences that will end essentially the same way.

Yes ships are disposable, but I think it is a result of how other gameplay factors are balanced. You cannot change one factor without affecting the others.