>>715230232The thing is, Warframe SHOULD be a proof of concept to a lot of other dev studios and publishers.... but it's not, for whatever reason.
Half the content in Warframe is the skins, so making nearly all of them available through playing the game was a master class level winning move by Digital Extremes. Most people probably buy 1 or 2 (or maybe more) skins and then grind out the ones they think look cool but they wouldn't necessarily buy with money. That is how the longevity of Warframe is secured.