User blog comment:Echo 1/UNSC Weaponry seems unrealistic/@comment--20100715080359

Not to mention less difficult to maintain. The more complex the device, the longer it'll take to fix it.

DEWs were not bought into service with the UNSC before the HCW probably because the UNSC would have no reason to develop them.

Lets step back for a sec, and note is that, it too mankind 100 years of constant warfare, before the first "modern" rifle was even devised. Same thing applies to UNSC pre-war; they had no 100 years of constant warfare, and no need for less effective, technologically advanced weapons to kill Innies.