Well, the suggestion I made takes a swing at these things to some degree; the 300 rig cost takes out some % of either tank or agility, the reduced lock range and time creates a nuicance which you may have to compensate for with a lowslot or midslot, warp stabs have a 40% penalty to these effects. So instead of getting the nullification for free you have now paid quite alot for it in slots.
As for the combat capability of the interceptors, a swarm of anything can be just as deadly as a swarm of interceptors - sure they can zip around alot quicker than most ships, but static bubbles can be blown up or bounced around / flown through. Also remember that citadels love spreading those points around, so any objective based gameplay is not really affected by the nullification.
My suggestion is also a way to mix things up abit; a fleet of nullified ships in a defence fleet will have it’s disadvantages, but will also be capable of warping off when getting redboxed, regardless of bubbles, this makes for slightly different approaches to how important interdictors are. Do you nullfy a logi, or do you need that rig slot for cap rechargers? Droneboats are not affected by the target issues when dronebunnies are used, is this op? T2 command destroyers doing kidnapping jumps and actually pointing things may be alot more effective than this braindead sabre spam.
Nullified machariels will blot out the sun; except bombs on a gate where you know they went through are bound to hit a few, and with their increased signature; long range dread can suddenly be a viable alternative with missiles (lol?). The point is, this is what I’m going for, take the idea I had and run with it, see if it fits into whatever whacky idea you have. Are nullified mackinaws too overpowered, etc.