I would say augmentations/artistic license. Its hard to make armor suits in cosplay, let alone Halo's MJOLNIR. It has lots of angles and edges so I imagine it takes alot of time or money or both to do it. They probably made the cosplays and just got people that could fit into them to wear them. IMO they looked CG or fake when they were on the Pelican so I may be completely wrong.