Realized I never replied here - yeah, one thing I want to do is look at the DP of the larger drones. (The small ones are not going to be much good regardless.)
Adding "Rugged Construction" to them may be worth a look, too, since we're likely looking at a drone-junker style if these are involved.
Rugged Construction certainly fits their lore, but from testing I wouldn't say they're
limited to a junker playstyle; I'd argue the Rampart is most usable with a build involving makeshift shield generator and hardened shields built-in, further boosted by an (Alpha) AI Core with Shield Modulation. I suspect a similar strategy would work for the Berserker, albeit held back by the inefficiency of 6 DP + 5/7/10 for the AI core meaning you'll have generally 2-4 of them in a fleet at best.
My whole argument for 'free vs skill limit' is that you could then have a fleet of, say: 1 Alpha Rampart, 4 Gamma Berserkers, and fleet-limit-filling amounts of dinky uncored drones and hit your 30/30 leaving the CR pristine. On the other hand if Ramparts/Berserkers/etc. were halved against the skill limit, you'd only really be able to comfortably have... 1 Alpha Rampart, 1 Gamma Berserker and maybe a couple uncored frigates before the skill's limit starts knocking down the CR to stat-lowering levels.
The 'abusable' cases of them being free, such as someone choosing to have 6-8+ Gamma Ramparts in their fleet, would already be kept in check by the low quality of Ramparts combined with the vessel having 25 DP (which is actually close to fair value when it has an integrated Alpha with an s-modded loadout), and as someone mentioned could be solved by lowering the impact of AI Cores on battle DP limit calculations (or in the case of Cored Explorarium drones, specifically lowering it for them).