I love the way you analyse things, you must write great essays
Well, I shall explain why I relate the title "guilty" to "victimism".
I'm used to deconstruct the meanings (I study Criticism at the university and my favourite is deconstruction so... I can't help it

)
I relate the meaning of "guilty" with those of "forgiveness", "regret"... If you feel guilty for something (it doesn't matter why), you may expect redemption and forgiveness from the others.
A guilty person is someone that has done something (he or she is the
subject), but, if we take into account the idea of forgiveness, that "guilty" person becomes the
object of others forgiveness.
She claimed to be (miss)understood already; now she expects to be forgiven. OK, she has said it in a very subtle way, but to me, it has been implied.
In my opinion, this creates a certain uneasiness to her audience, to their fans.
(this is just my opinion, of course)
As I write these lines, I realise Ayu establishes a dialogue with us through her titles (well, I suppose I already know this,
and you too, but with this title in particular, I think it is even smarter, stronger and relevant).
BUT, ok, let's study the title from
another perspective.
It seems to me that playing the role of Ayumi Hamasaki involves a great effort to Ayu's persona (using really well chosen word by namiie). She is constantly fighting (we read it in her lyrics), and she loses sometimes. I am sure she feels she has lost some of her true identity through these years. And she feels guilty for that...
has it been really worth of it? This is one of the possible reasons for that guilt.