But what actually makes it look modern?
Is it just better film stock?
Make up and costumes play a huge part in how film can look aged. Its why some 90s stuff looks even older, its just a bit alien. John Conner hair maybe ages it a bit but quite honestly Hollywood and child haircuts is fucking weird in America and seems to have a ban on anything short and has a strange fetish for the bowl cut.
Compare Sarah Conner in 1 and 2 and basically you see what ages a film outside of just camera tech/lighting etc.