PvP ships are not compromised because they aren't making compromises for the thing they're built for whilst the "traders should have sufficient shields" means trading ships are being compromised for the things they're built for.You can fly a shieldless trader in Open if you have the skills to avoid interdiction in the first place.
The "PvP ships aren't compromised" argument is silly when it's kinda in the name that they're PvP ships. They're obviously compromised at exploration and trading.
Likewise a trader is compromised at PvP because it is a trader.
Choose open or don't, but if you choose open and don't outfit or have the skills to back up your big brass balls shieldless T9 at a CG, don't whinge when you get easily popped by a railgun Adder.
It's not rocket science lads.
It is not whinging to point this out. It is merely pointing out a weakness in the game design. There should be pros and cons to all. I have no problem with the idea of traders having to decide between running with a bit more protection or more cargo space, and accepting the balance of risk versus reward changing as those factors change. This isn't the case with the PvP build though, the owner of that ship isn't having to decide between two things he wants when he puts it together. A practical reality of having to compromise is good.