While I think it's obvious to pretty much anyone that his voice isn't what it used to be, I don't think it is simply about "high notes."

Sure, they matter, but they aren't everything.

If you listened to much of the Crush tour(try the Crush DVD even), there are times when he is simply squeeking notes out his nose and really slurring the words. That concerns me more than a reduced range, though they are probably related. Personally, I think there was a genuine vocal problem because at times he sounded horrible(VH1 Storytellers is a great example) during the Crush period. I also think the vocals on the Crush album are inicative of how the future tour was going to go.

That said, he sounded better on the OWN tour, and much better on the Bounce tour. No, he didn't really go for any of the really high notes often, but he consistently sounded better and performed the songs convincingly. Judging by the web casts at the end of the Bounce tour, his voice was under considerable strain and he was reverting back to slurring the words, and absolutely butchering "These Days." That doesn't concern me too much as it was the end of a lengthy tour and he sounded great a few months prior to that the times I saw him. I think it was just a tired voice that needed rest.

I also really like the sound of his voice on TLFR. It's warm and inviting, rather than nasally and piercing.

I don't think his voice is "lost," but I do sometimes wonder if he notices what fans are noticing and, if so, does he care. Obviously he does, but does he care enough to get serious about vocal training and laying off things that damage it(smoking..).

In fairness, if we weren't complaining that he didn't sound as good, we'd be complaining that they weren't touring enough. It's the constant touring that is probably the most likely culprit in why it sounds so different.