the short story was a good move, putting in-universe fiction where everyone can see it. they could probably use that tactic online to help encourage interest in the game as well, as a sort of advertising for the game line and books.
for mechs in a box, the bigger cost is in the molds. so they have to sell so many boxes to break even, before they can see a profit. the return of the unseen mechs is a big deal in itself, but there are a lot of options. for example, if they included a number of tanks (small, easily explodable tanks) alongside some mechs, say 1 or 2 lances of mechs and 2 or 4 lances of tanks, the smaller size of a tank would make it easier to fit in the box. two tank models, 4 of each, and you could probably do that with one mold (tank body A, tank body B, turret A, turret B). maybe some cardstock buildings, to give a more 3D sense to the map.
I love the marauder but its a pain to assemble. from a logistics viewpoint, the marauder is a bad choice. the last time they did a plastic marauder it had a massive gap down the middle. as much as i would love to see a good plastic marauder, now may not be the time.
it may be a good idea to consider the scorpion as an option. its a fast medium with PPC and SRM, and being a quad it can go hull down like a tank can. throw a couple of those into a box with some tanks, and you can get a very different sort of armored combat.
a boardgame with tanks and giant stompy robots, plus a couple buildings, would be very interesting. you could do a lot with that- attack/defend the building scenario, or just use them for urban cover. throw in a story with a mixed company maybe.