This. So much this. Plus, the original idea was to have something that could defend our conventionals from a Kaiju closing with them, so as to not suffer major losses. Traps help prevent that, either by weakening/killing the charging Kaiju, or by delaying it.
That said, correct me if I'm incorrect, but most of our losses of conventional units to Kaiju have been to ranged attacks, and not melee charges, yes? And we've already seen that the Hlin cannot entirely prevent this outcome. Might I suggest that either building more Hlins, or improving the Hlin's shields, is a higher priority?
Much as I love the idea of using of remote-detonated mines and mine-fields, we have a rather massive list of things to research and develop. One people seem to not be consulting all that often, which, given that I've been mostly dumping my new ideas on there, rather than in the thread, is a bit of a problem. I've got an interesting line of investigation on single-pilot Jaegers on there (or, rather, a hybrid system where an AI, derived from Jagdhund's OS, Drifts with a pilot), amongst other things.