1. a CZ is a place you choose to go. there are other options to win a war if you don't want to that.
2. while CZ ships got upped in terms of hitpoints, none feature engineering, besides the targets of CZ objetives (spec ops wing, enemy captain). CZ objective targets don't even count for CZ missions, so enganging them is very optional. and objective is worth ~4 shipkills.
the exampel "but CZ ships where upped" is just not very good.
your suggestion is upping/introducing NPC, who should interdict players while doing powerplay, with increasing engineering by players powerplay rank.
again - the situation would be very different, if you'd suggest having people flying non-engineered adders, eagles and sidey at rank 5.
that would not gate rank 5 powerplay to horizon running commanders. it would certainly make things harder in all modes. and it would make most, if not all npc for all powerplayers in all modes more challenging.
as for ATR - yes, that is a good exampel. ATR in fact gate pve murdering BGS gameplay to people running engineered ships. still - you can of course leave the controlling factions space. and you can choose other means for similar or even more effect when influencing the BGS than a murder spree. i see no such suggestion in yours.
probably as you suspect as i do, that if your suggestion would include a way to bypass those "special agaents", most players would do it.
You are not thinking globally though- a CZ is a local battle- project that out to the bubble in size and it encompasses Powerplays game 'board'. Plus, Powerplay has places you have to go to as well- combat expansions (themed CZs), expansions, preparation areas and capitals, as well as the BGS aspect.
I mention spec ops because thats how it should be- ships equal or better than yours stalking you. These NPCs have to make you sweat, they can't be anything other than that.
I don't agree with having players in smaller ships- firstly, why after years of engineering and tuning ships you throw that away? Powerplay should test you, your ship and your game knowledge, it should offer something above and beyond a CZ, wing mission, Thargoid or CG. Otherwise, whats the point?
The difference for this idea is that you can't switch off ATR like you can in the game- playing to a level keeps that level of threat consistent and is persistent- the only way to stop them is to back off (as its scaled to effort).