Also, in the same vein.. if you increase ship defense values I would also prohibit carrier based fighters from having any defenses. This will still make them very powerful but also allow for some losses in battle, the fighters would focus on those ships and likely have to make multiple firing passes killing the ship but not before it and other ships can reduce or eliminate most of the fighters.
On a separate idea, why not use strategic resources for improved defense values. I would GO OUT OF MY WAY to get a (resource) that gave or improved shields on my ship that reduced beams 25 or 50%!!!
Also what about cross resource defense specializations? Durantium can improve armor but in the 'Shields' line there is a beam augment that uses Durantium to boost shields 100% or whatever.....
Just brainstorming is all..