The thing is, they take on a bizare internal literary significance when you start thinking of each part as one of the three virtues.
-Pretty much every challenged faced in 2001-2003 is solved by the toa's UNITY. It's very much the UNITY of the island of Mata Nui that Teridax seeked to break. In addition, this is the only era of bionicle when there is a heavy focus on Kaitas.
-2004-2005 focused heavily on the toa metru's DUTY to the matoran. Lhikan's DUTY to the island was what drove him beyond everything else. The major conflict in WOS was Vakama forgetting his DUTY to the matoran. Sure, the toa metru were destined to transform, but it is their DUTY that that implies that takes on a greater significance. In fact, if I remember correctly, all the Toa Metru, besides Vakama, believed that they were not the truly destined toa, and yet they did their DUTY anyway.
-Ignition was heavily focused on the DESTINY of the characters, specifically Matoro and the Nuva. In addition: several story mechanics depended on destiny. Pit mutagen works IF YOU ARE DESTINED TO TRANSFORM, if I remember correctly. You can only use the ignika IF YOU ARE DESTINED.
-aaaaaaand Bara Magna makes no sense here
This was the result of zero fact checking and stuff I remembered off the top of my head. also nostalgia goggles. I just thought about this and found it cool.