So since we now know there are multiple companies that manufacture GEN2 MJOLNIR like Material Group, Acheron Security, Naphtali Contractor Corporation, etc. Why not each manufacturer make their own style of armor? Of course, to keep equality, all armor variants would still have similar features like energy shields, thrusters, etc.
For example, Material Group could make an undersuit like Halo 3/Halo Reach’s while Acheron makes an undersuit like Halo 4’s. Same thing for outer armor too. NCC could do a completely new look to MJONLIR while another company makes a version of MJOLNIR we’ve seen in previous Halos. All undersuits and outer armor would be compatible with each other so players wouldn’t be limited to their choices and players that prefer different styles of armor could mix and match company styles or just stick with their preference. Like if I wanted to wear Rogue, but I wanted the Halo Reach/Halo 3 undersuit, I could wear Rogue on top of that.
This could work in canon too to explain why there are so many variants of MJOLNIR that one would figure all serve the same purpose. For example, Materials Group could produce EVA while Acheron Security produces Orbital.