Also worth noting is that an entire wave of army builders is a terrible idea. From Hasbro's perspective, they want as many people to be 'all-in' on collecting Marvel Legends as possible. They want to attract not just 'I collect X-Men' or 'I collect street level heroes' types. They want to appeal to people that collect the entire MU.
So they'd be asking that core demo to buy multiples of EVERY figure in a wave? Maybe if we were getting fewer waves per year. It makes way more sense for them as a company to release them on their own (as Slixta said) or to make them non-BAF figures (or do them with BAF parts you can get multiples of, like the Hand Ninja). An entire wave of army builders would be a huge risk that they'd be insane to take.