Maybe it's because I play with so many bells and whistles, but I've never seen the point in the warp jammers or destroying warp gates. There's always threat, hybrids, exo-waves, freed guard units, antagonised Dysons and whatnot coming from all directions; and waves arrive after an announcement that almost always leaves enough time to ship some defensive units over to where they're needed.
Well, such is my experience, anyways. Maybe I'm just doing it wrong.