We all probably remember throwbots. They were good at that time until Bionicle came along. Bionicle showed us a whole new world of the kind of quality Lego could produce (besides the whole Bohrok-Kal thing). Throwbots beacame a stepping stone for Bionicle.
But now, Bionicle is going back to the old disks! I know there are mixed opinions about these, but i think I know why they are in the 2004 storyline.
Since the new storyline takes place in the past, I guess the collectible for the storyline is from the past too.
I'm not saying that Lego meant to do this or that Lego's product line in any way represents the Bionicle story line either. I'm just saying that it is kind of a coincindence that the storyline AND the collectible are both from the past.