For a long time the outfits worn in battle by Mitch and his team were - for all intents and purposes - their civvies. I decided that this had to change. Since they are an official part of a well organised military force, they needed a uniform to give them an image of professionalism and discipline. Their regular outfits made them look more like a mercenary team, which was misleading juxtaposition against the good guys - who are an independent unit - use a standardised uniform. Plus, a common uniform means I only have to design it once and don't have to come up with different designs for all the characters. For a while the battle suits the good guys wear were all different. I'm glad I later standardised it.
The uniform of Mitch and his team is based on the attire their human counterparts wear, but with a few alterations to make them stand out and be unique, with the practical reason being that the equipment allocated to them is custom designed for their duties.