Some aspects of TOS have aged poorly, but we are starting to get distant enough from the era now that its coming back around the other side as a sort of esoteric aesthetic. Until the space hippies episode.
I think the strongest argument for how well TOS' look aged was the 1701 and Defiant's appearances on DS9 and Enterprise, respecitvely. Using then-modern cameras/lighting, the TOS set designs were honestly beautiful, and did not seem out of place or dated on series with 1990s/2000s production design.
I'm not sure if the DS9 or ENT interiors will hold up that well some 30-40 years from now.