Why Do Weyland-Yutani Want The Xenomorph

Firstly, I know you're all think I've lost it and are planning on posting something like "They wanted it for their Bio-Weapons Division", but hold on a second... [b]Alien[/b] We know that Ash observed the Facehugger stage with intent and that he knew something was gestating within Kane, and later on Ripley discovers Special Order 937. But nowhere in Alien does it state that Weyland-Yutani wanted the Xenomorph as a bio-weapon. The only references to creature come from Ash, stating it to be "the perfect organism". [b]Aliens[/b] Cutting a long story short, Carter J Burke was sent with the USCM marines to execute Special Order 937. But when confronted by Ripley he never states that the Xenomorph specimens he desires are for the Bio-Weapons Divsion, just that they would be worth millions of dollars to the aforementioned division. This shows... 1. He was motivated by greed. 2. He was on a need to know basis. 3. His being on the mission reveals he is considered expendable. [b]Alien 3[/b] Although in the "Assembly Cut" Ripley does state that W-Y want the creature for the Bio-Weapons Division, this would be an assumption garnered from Burke. When the W-Y rescue/extraction team do arrive they never actually state that they want it as a weapon. [b]Alien Resurrection[/b] Again there is no reference to using the creature as a weapon. There are references to new alloys, medicines and domesticating the creature, but no mention whatsoever that the intend to use it as a weapon. ...So why did the Weyland-Yutani Corporation and United Systems Military want the Xenomorph so badly... Is this related as to the mystery of why the Engineers need the Xenomorph?