I think the main issue with building these structures is that they are simply outranged by too many cheap counters to ever be useful, combined with the fact that ZK has the least terrain-dependent gameplay out of anything on the spring engine.
Spiders, jumpbots, and strong air make chokepoints pretty obsolete.
Let's take BA on DSD for example, as most spring players are familiar with the gameplay that has developed on that map. North can build porc on the hills in the north, and south can make porc on the flat section. Each side is narrow enough that a single annihilator set up in the middle of that section is enough to cover the entire section. It's almost impossible to go around like in ZK because:
1)T2 spiders suck in BA. They are very limited even when on hills, and SUCK on flat ground. By comparison, ZK spiders are very strong, even on flat ground. T3 all-terrain in BA is expensive with a 9k metal lab required to even start building them.
2)Bombing in BA is difficult because fighters insta-counter bombers in like 2 shots. By comparison, bombers in ZK can often bomb deep into enemy territory and fly back, fighters chasing them the whole way and barely doing any damage.
3)Jumpbots dont exist at all. The ability for some pyros or a sumo to simply jump over hill can't happen. By comparison, ZK sumos and pyros can simply jump over hills and go into enemy base.
Since none of that stuff can happen in BA, annihilators, doomsdays, and behemoths are much better at what they do
without even being more powerful. They can sit there and hold off a section of the map that nothing can pass. It's the TERRAIN that makes BA's superporc weapons so much better than their ZK counterparts - units are forced to assault them head-on instead of just going around them. Think about chickens - annihilators are actually useful in chickens because the dumb chickens will assault them head-on time after time.
Outside of some major, major overhauls to ZK gameplay, the only way I can see to make superporc weapons better is to make them about approximately current cost but without grid requirement. The grid requirement is already a noobtrap to begin with and it makes the towers extremely difficult to place effectively. It also makes them entirely too easy to disable - I saw an annihilator completely shut down because a single wind generator was destroyed, destroying the link to the power supply. If they start getting spammed too much, you can always adjust the cost later.
Conclusion: the best way to make the superporc weapons more useful is to make their placement easier by removing grid requirements. By allowing them to be placed anywhere without a grid link, it removes a chunk of unnecessary logistics and makes the game more accessible to newer players that might not understand the grid or the power requirement. It allows for easier placement in places where spiders or jumpbots normally get a free pass.