I love new chain day; drivetrain is so quiet and smooth.
Back in the day, Calvin Jones, formerly of BBI, said "Remove that sludge the chain is packed in, that's just so it doesn't rust on the long salty boat ride across the Pacific". So even though I had ridden with the factory goop and liked it, Calvin was the teacher, so he must be right. I started painstakingly de-greasing and re-lubing my chains right out of the box, before I even turned a pedal.
Fast forward a decade or so, and now experts are saying the stuff the chain is packed in is factory lube and is the best thing you can run a chain with.
Maybe this is one of those chicken or the egg debates. Or the age old grease or don't grease your BB tapers. For you youngsters, bottom brackets and cranks used to fit together with a "square taper" joint; the crank arms would essentially be forced onto the bb as far as they could go and held on with friction and a bolt. Some people believed if you greased the tapers your cranks would fall off, others felt if you didn't they wouldn't slide on far enough, or never come off.
I'm glad it's ok to leave the goop on again; it makes it soo smoooth!