You pretty much described the die-hard PVP crowd there. They are the min-maxers, the ones who put tiny FSDs on their ships to gain a few m/s extra speed, so they brought this pretty much on themselves. (Sorry, not being spiteful, just calling them as I see them.)
I USED to have stuff like collectors etc. on my fighting ships, but now, given that I might go to Open, I stripped all that out, put in the biggest SCBs on my corvette, and crammed it full of HRPs and MRPs.
It makes sense, too. A warship is bound to be geared towards that job, and ONLY that job. What on Earth would I want with THREE size seven slots if I couldn't put SCBs in two of them? Cargo racks? Nope. Warship. I DO have a corvette outfitted as a cargo hauler, but my fighting corvette is highly specialised.
I understand that balance is necessary, but the point is: warships should have a clear, dedicated advantage over less specialised ships, and, frankly, I yes, you could, obviously, severely restrict SCBs, HRPs, MRPs, SBs and so forth. What would happen? Inevitably, the PVPers would quickly find a way to max out their ships, and this time, the ordinary folks (like me) would have far less defences at their fingertips.
Naw, I think I'll pass.