Crown presents the triangle as one of the motives. And it's important to demonstrate that there was a motive in the crime. For example, a one-legged man that has only the left leg could argue that there is no point for him in stealing a right shoe, as he can't use it and the market value is negligible.
At the same time, motives can be less trivial. Would anybody argue that Russel Williams stole panties for personal use (imagine those under his uniform)?
Here is an excerpt from Bundy's wiki page. I find this relevant. Notice theft and the thrill of possession, as well as progression in his criminal behaviour. Does this ring the bell?
Shortly after the conclusion of the Leach trial and the beginning of the long appeals process that followed, Bundy initiated a series of interviews with Stephen Michaud and Hugh Aynesworth. Speaking mostly in third person to avoid "the stigma of confession", he began for the first time to divulge details of his crimes and thought processes.[SUP][231][/SUP]
He recounted his career as a thief, confirming Kloepfer's long-time suspicion that he had shoplifted virtually everything of substance that he owned.[SUP][232][/SUP] "The big payoff for me," he said, "was actually possessing whatever it was I had stolen. I really enjoyed having something ... that I had wanted and gone out and taken." Possession proved to be an important motive for rape and murder as well.[SUP][233][/SUP] Sexual assault, he said, fulfilled his need to "totally possess" his victims.[SUP][234][/SUP] At first, he killed his victims "as a matter of expediency ... to eliminate the possibility of [being] caught"; but later, murder became part of the "adventure". "The ultimate possession was, in fact, the taking of the life", he said. "And then ... the physical possession of the remains."[SUP][235][/SUP]
Bundy also confided in Special Agent William Hagmaier of the FBI Behavioral Analysis Unit. Hagmaier was struck by the "deep, almost mystical satisfaction" that Bundy took in murder. "He said that after a while, murder is not just a crime of lust or violence", Hagmaier related. "It becomes possession. They are part of you ... [the victim] becomes a part of you, and you [two] are forever one ... and the grounds where you kill them or leave them become sacred to you, and you will always be drawn back to them." Bundy told Hagmaier that he considered himself to be an "amateur", an "impulsive" killer in his early years, before moving into what he termed his "prime" or "predator" phase at about the time of Lynda Healy's murder in 1974. This implied that he began killing well before 1974though he never explicitly admitted doing so.[SUP][236][/SUP]