I immediately agreed with what you wrote, but now there's a voice in the back of my head asking "if this is so obviously right, why is it just happening now, af

I immediately agreed with what you wrote, but now there's a voice in the back of my head asking "if this is so obviously right, why is it just happening now, after 2.0? It's not like this Lattner guy doesn't know what method calls cost..." A post last week featured Lattner writing about Swift treating methods as final when they weren't declared that way (https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20151207/001948.html https://lists.swift.org/pipermail/swift-evolution/Week-of-Mo...). I wonder if the early thought was that they'd get enough mileage out of those "cheats", and then later decided that final should be the default.