complexes have, without a doubt, been one of the leading sources of pvp content and countless 1v1 opportunities. PvE is not the answer, my friend. PvE has and will always call for maximum efficiency fits that are incongruent with pvp meta.
p.s. There is nothing wrong with complexes or their role. The problem is getting pilots into them. Even though they offer militia pilots the opportunity to fish for a fight, while also serving as a back alley of sorts, a limiter for what an opponent can bring against you, and rewards you even if you don’t get pvp content, it still takes much too long to complete a site or take a system. Two full days of constant pressure is quite a bit for some folks now that a citadel can give someone a perch to squander that investment of manpower.
It’s not worth it. The reward is not what it used to be (no lock outs, no pushing them out into high sec), no recognition (no more legit medals), no penalties.
Losing has lost its sting, victory its laurels.