(ER) Medium laser is far more useful as a rear-facing weapon than M-pods. Hell, the SRM is far more useful than an M-pod. If there has to be rear-facing weapons for style, keep them as lasers.
Both range and logistics is at play here, more range is simply better and one-shot weapons are a logistical complication. A laser solves both very neatly.
A one-shot weapon is almost never an upgrade, and one-time potential for high damage is not really useful unless it is enough to breach enemy armor or even cripple them (massed rocket launchers).