We're definitely seeing a change from when there was a very particular visual 'language' required for covers, due to the importance of needing the cover to sell the issue on the newsstand.
Real effort went into their composition, an almost psychological-level consideration of colour choice or wording, in addition to whatever business decisions were in place regarding which designer would get featured etc.
When you get a situation where there's a thousand practical compromises being made in order to get your issue out the door, but there are also people at the magazine who believe in never compromising on design, it can all come together to produce something exceptional. It's the cover as elevated to an art form.
So much of that has fallen away, because magazines seem to have decided there isn't the same requirement for it in the first place.
Also, the deceptively simple nature of Franca's Vogue Italia has led everyone to believe that taking an interesting image and putting one or two words over it means you've created a stunning cover.