A well crafted song is a well crafted song regardless of when it was written. That is why modern artists are covering classic songs daily.
Modern music being interested? Well that's your opinion. Modern pop being more diverse? Well you're simply misinformed because there are a number of studies that show that modern pop has few different sounds, fewer chords, fewer different chord progressions, and fewer hit singles than any point in music dating back to the 50's. And as far as rock and pop being the same? They may overlap at some points but a generalization is just flat out wrong.