Well, aside from even lore building, there is merit in gather ancillary information. Cortana Letters, were not really that important to the lead up to CE, but I'm still glad we have them. For posterity's sake, I think its a good idea to get as much info as possible. Maybe we will look back at this with nostalgia like we look at ilovebees.com and IRIS. IF we missed things, there would be less to look back on. Past that, I think there is also a plot working its way out to something here. Perhaps the back story. Just as you did not get the full story of Halo without ancillary media (novels, terminals, ARGs, etc) we might not get the full picture of Destiny without this ARG.