Given JW beliefs, it would be so much more practical for the speaker to simply ask that anointed ones in the audience raise their hands so that attendants can bring the emblems to them alone so that they can partake; instead of indiscriminately passing the emblems to everyone in attendance.
But Watchtower doesn't want that. Watchtower is aware of the fact that the non-partaking of virtually everyone in attendance is a conspicuous contrast to Jesus' instructions to his disciples that they partake. Since most congregations have 0 anointed ones, following the above procedure would mean never passing the emblems at all - further deepening the contrast and showing up the JWs.
By having the emblems passed, Watchtower is working a bit of psychology on JWs. JWs are being given the subliminal impression that they are participating in the event - that they are personally asserting acceptance of Jesus' sacrifice by handling the emblems. Passing the emblems also creates an atmosphere resembling one of partaking. Psychologically speaking, it's like they're compromizing / softening their disobedience of Jesus command. "We did pass the emblems like Jesus commanded".
This further highlights the fact that JWs are all about appearances. Even while disobeying Jesus' command to partake, they make sure to do all in their power to give the subliminal appearance of partaking.