IMO the Ramseys needed a doll that if the police asked for and tested could not be associated with the death of their daughter.
The way the dolls are made there is a vinyl head attached to the cloth body with a cord. The cord ends up hanging down the back like 2 strings. The dolls hair can get tangled in the cord when brushing the hair. It was not a big issue but during training I was told to tell parents they could pit a piece of duct tape on the back to alleviate the problem, never pin it and never cut it. Don't think I ever had any calls or complaints about this but did remember the training and when the end of PMPT stated how that little piece of duct tape proved an intruder did it, it had no connection to the Ramseys but here was a credible link. Why remove the dolls at all? Dead children don't play with toys. Jonbenet's favorite toy was a stuffed cat that they didn't have Pam remove. The dolls may have looked innocent but IMO they tell of the pure evil in Boulder.
At first it was just about the duct tape having a connection to the dolls the Ramseys removed. Then I experimented and put duct tape on a doll and pulled it off, it left half the adhesive on the doll in a stain and the tape was missing half it's original adhesive. The tape also pulled out some white stuffing and there was a tiny imprint of the woven tan cotton fabric and a bigger imprint of the 2 cords, as in the lip prints Steve Thomas mentioned. There was a visible stain on the doll a mirror image of the missing adhesive from the duct tape. That could have been why the Ramseys removed the dolls. Or the fibers found wiped on Jonbenet, one doll had an outfit of navy wool with copious short fibers that shed like an angora rabbit. Was she wiped with the doll clothes, again another sinister connection to these dolls.
Years later it was revealed tan cotton fibers were indeed found at the crime scene. Genius detective Smit thinks the intruder wore tan cotton gloves, I think it's far more likely the tan fibers are from one of the doll's tan cotton torso, the dolls removed by the Ramseys. The dolls were removed before all the evidence reports were in, it was still early stages, it was still the collection process.
It's possible the dolls have no connection but considering the extremes the DA went to not investigate them makes a conspiracy far more likely.