I think being deemed "worthy" by the Siege Perilous was VERY much about wish fulfillment, albeit with a twist in some cases: Rogue was separated from Carol Danvers, Peter became an artist and Alison a star. It's a bit harder to understand Alex ending up in Genosha, but I always interpreted it as him seeking respect and also wanting to get away from the madness his life with the X-Men had become. Elizabeth's fate was dictated by her desire to be a true warrior and a physical fighter and to me it was very much a natural evolution of her character. And in her case the Siege's twist was that she ended up not looking like her former self.
If you read the Uncanny X-Men issue where Betsy fights Sabretooth and joins the X-Men, she wonders how she can show the team "the tiger within"; and again in the already-mentioned annual drawn by Alan Davis, her "heart's desire" is to be transformed into a metallic warrior. Ninja-Betsy made so much sense to me when it happened because it felt like a natural progression for the character.