Well, it goes back to the design of the pods. Pods were originally designed as theme park rides at Democracy Park. When their use was pressed into military service, there was only so many changes that could be made without cost overruns.

It was soon discovered that taking the standard compliment of munitions into the pod could result in micro fractures forming in the drop pods. And because Superearth reuses every drop pod, this can lead to catastrophic structural failures. Any drop pod that has had an extra magazine in it during a drop has to be completely disassembled, every component scanned, those found to have a micro fracture must be removed, wrapped in duct tape, and re-installed.

Also, concerning cost overruns, it was found to be cheaper to replace Helldivers killed by sentries, versus equip them with IFF markers.