One would think if there's money to be had from charging for more vault space than the crew would be comfortable devoting time and energy to it when only half the user base would want or need it at this juncture, because it'd be more profitable than waiting until almost all users want or need more vault space because when most users feel they need something to continue, they'd expect it for free in an update or expansion, but while it sits at around half the population now that want or need more vault space, the company can (re: should) be able to code into the cash shop an option for extra vault space at a fair cost, as half the user base would pay for it as it is now, and feel comfortable continuing to progress, lest they feel the need to take a break or leave altogether due to not being able to store what is to be sought in activities, co-op and competitive alike. The longer the company waits to implement more vault space, the more it'll hinder (or at least remain stagnant when there's money to be had in this window of opportunity) the bottom line, and thus funding for future projects, etc.. Cash shops are supposed to be purely cosmetic in most implementations and, generally, for the hardcore user base and the more users that want a particular feature, the more it is on the company to deliver said feature for free to all, so striking while the "iron" (pun intended) is hot, with roughly half the user population wanting or needing extra space now (or some, such as this user, for quite some time actually), there's money to be had, and less when most expect more space for free.