I think you misunderstood what I was saying about singing. I never said they CAN'T sing, I just said that they tend not to do interesting things with their voices anymore. Plant would manipulate his voice in cool ways to add more depth to a guitar part or whatever. It's hard to explain, but I didn't mean that vocals lack emotion now (I've seen that guy from Korn break down crying after a performance).

But I stand by what I said about mainstream music's lyrics usually (not to say all the time) lack substance to them. Keep in mind, most of these bands (all the popular boy bands) don't even write their own lyrics.