There was a lot of functionality added so to address this, they reduced the contrast of all the fonts? Nope. A more likely story is, as they added more functionality they delegated what could have done by people with less skills than a programmer because there are not enough of them. The end result is the people who care about well something works are just working on the program. The rest of the hangers on are trying to make their mark by using uber cool typography. I'll be the first to admit the lighter fonts look cool but they don't help you with your real job.