Some problems with that:
The Macross' fold drives (Which can be supplemented by the ARMDs' drives) use a lot of energy, and during fold operations, only primary systems remain online. It can only fold after several hours (Was it 24, originally?) pass, so it can charge the drive's capacitors. The same is said for the cannon. It must charge up, and even in NMCs, it can only fire once an hour. The ARMD's drives aren't powerful enough to fold the whole Macross, or so I read somewhere. If that were the case, it'd be awesome. This invokes memories of Max Jenius ordering the Macross cannon fired in empty space, and hitting a folding fleet as they defolded.
David: ECM, while technically Active Stealth, creates a large buble of empty radar. If their planes fly into it, they disappear. A lot of the time, ESM can detect these bubbles and it's only a matter of time before the ECM plane is taken down.
My grandad was a weapons loader on an ESM Plane in Vietnam...