Not that I am surprised, nor am I complaining. I'm quite glad that they did not, since it keeps Barrie's distinctive from their version. Not to mention my extensions of Barrie, for Mab is an important character in Peter Pan: Betwixt-and-Between.
Then again, Barrie's not responsible for creating Mab. She's first seen in print by Shakespeare in Romeo & Juliet. (Curiously, though, Shakespeare also names the fairy queen as Titania in A Midsummer Night's Dream and there she is the wife of Oberon the Fairy King. ) Queen Mab has made the rounds in other stories and literature since then. Why, then, did Disney not use her? (Again, it's a relief that they did not!)
Know what else is curious?
In Barrie's world (of Peter Pan) there is no fairy king. At least not by name. We only have this passage, which does not seem to relate very well to the rest of the tale [in that there's no other mention of him and it comes suddenly in the text]: They went through the form of thanking her—that is to say, the new King stood on her body and read her a long address of welcome, but she heard not a word of it. Naturally, I have my own theory regarding the Fairy King of Barrie. I can't help but note a word in that passage. The word? 'new' Why would Barrie point out that he is a 'new' king? Perhaps because he, well, is new? As such, to give a little away as to my own take on it, I suggest that Queen Mab reigns eternal and thus has a new king every so often. Of course, given Barrie's line in Peter and Wendy - I expect he was right, for fairies don’t live long, but they are so little that a short time seems a good while to them, there must be a way around that fact in order for that to be so. Well, since Queen Mab is not Barrie's own invention and she permeates literature and art throughout history, I am confident that she is an exception to Barrie's rule. But in order for that to be so, there must be a reason for it in Barrie's world, no? Of course, and I aim to make that reason known, eventually.
I have a slight hint of her immortal status in Peter Pan: Betwixt-and-Between, but in the tradition of Barrie it raises more questions than it answers. Don't worry... it will be brought up again one day -- in a forthcoming NeverWorld book. Yes, Queen Mab will show up in that series as well. It seems Peter Pan's 'true' fairy Denny will face his own light starting to dim and need to unravel the riddle of her perpetuity if he's to remain by Pan's side. [His quest will be a side story within the novel in which it appears, which I'm thinking will be in Book 3.] And for those who think I might be clogging up the works with too much filling-in... I assure you the answer is very simple.
Perhaps I've said too much already?
Queen Mab on Wikipedia
Illustration of Queen Mab by Arthur Rackham