By the power of truth, I, while living, have conquered the universe.
Posted by: RKOSNAKE
I don't think the geas directed humanity to Reach, I mean, it's not really that important if you think about it. Sure, it's humanity's military stronghold, but apart from that there's nothing special about it, save the Forerunner artifact, but there's Forerunner artifacts in several other planets. So I say, coincidence.
Reach has a slipspace crystal, considered the norm for Forerunner ships but would be a massive scientific discovery for humanity. Why would the Forerunners would lock it away? The planet has clearly been augmented to become stable, it's only a billion years old (very young for a planet, compare it to Earth), along with a massive data centre (which would be a very likely place to house information due to the loss of the Domain in a place with a name that relates to the meaning of "a coming war"). All this considered makes Reach a treasure trove of convenient things.
A crystal for humanity to advance their technology and a data centre likely containing information about the Forerunners ("without that record, whould future civilisations know anything about us or only of our weapons?"). All seems a bit too convenient to be a coincidence.
[Edited on 12.30.2011 5:05 AM PST]