The problem with them hinting that we'll find out some juicy revelation if we keep reading is that it implies there really is something very interesting or unknown to further clarify. And it precludes the chance of the mundane. Something like Thom's blades flashing against the Myrrdraal's, for instance, takes something that could have just been an "oops, well, let's all just ignore it and get past it" and elevates it to a point where the reveal is limited to either Thom can channel or his blades were Power wrought or Thakandar wrought or someone mortal or divine intervened to assist unseen to the reader. And then you're left wondering, now how in the world is that factoid from eleven books ago going to come up in conversation in one of the final two books so as to be relevant?

Same with Cyndane's body. That they feel there's something worth holding back makes you abandon any thought of random body assignment and leap to one of two extraordinary possibilities of it either being the form of another character we know or even Mierin Eronaile's original form before she became the impossibly beautiful and powerful Lanfear. And if it doesn't turn out to be one of those two explanations, we're going to be disappointed by the let down from the hype generated by withholding the information for so long.