I might be speaking out of turn, here, and you can shoot me down if you care.
You'll probably find any ex-Servie (well, Army at least and for those that have Marines, I'll include them out of manners) would shun most of the gadgets "collectors" think are wonderful and necessary bits of kit. CES can be quire exhaustive and doesn't always get taken into the field (bush...) when you have to pack and carry it. You take the important hings.
Tests Of Elementary Training (TOET) for weapon handling requires the Digger (insert your National term of endearment for soldier) to hand load mags at a certain pace and accuracy.
Brens were no different. In later years when the Bren was superseded by the useless Automatic Rifle L2A1 (in AustralianService) the Dig needed to load the required 30 rounds per mag in a certain time frame.
Surprisingly, prior to the next action, all Section members would help the No 1 and No 2 on the gun load mags. It took far less time and effort than you'd think. And relieved the mind boggling frenetic move form boredom to terror and excitement.
While they're another physical accoutrement, they're not an item that you'd find many Digs worrying about. Nice to collect, but as Peter Laideler says another WAFTAM. (you can work that one out yourself...)