I also love her deeper voice much more, too. But the problem lies in her singing, not her actual voice. Many people think she is screaming all the time... Which I don't find to be necessarily true. For me, she seems to be having major difficulties in breathing correctly. Her voice often sounds strained or breathy the past few years, and yes, sometimes she does scream a bit (though, that isn't the main problem, as some seem to think).
Overall, she's singing as though her voice is just worn out and overworked. Which means there's a high chance that her voice is unhealthy due to incorrect singing in one way or another. And that's the worst part of all, especially if she doesn't try to fix it immediately (though, I think she must be). Also, because of this, a main concern for most people bringing up her "terrible" voice is that she will severely affect her ability to perform as a singer (at least, I hope that's why they're expressing these thoughts, and aren't doing it just to bash her, lol...).
But really, the past few performances have been great. Rule at Kouhaku was amazing, and most of the You were... performances were wonderful, especially for what it's worth (that's a very hard song to pull off live). I think she just hit a rough patch last year, and that she's working on fixing herself up as we speak.
And I mean, it's not as though she sounds as bad as she did around, say, 1998-2001, lol...... As long as she doesn't sound that bad, I don't think it's the end of the world or anything.