Remove the premium pass system altogether and make everything on the pass attainable with exp.
However, give players the option to buy the full armor sets and unlock them right away instead of collecting the sets piece by piece with exp.
I think this would be a reasonable and fair way to do the battle pass.
EDIT: this also obviously applies to other customization items on the pass. The AI and Spartan ID items like stances, emblems and so forth could be purchaseable in a bundle or collected over time with exp.