When new devices are first connected, they may need their ports reconfigured, but LLDP isn't turned on until it gets a configuration. It would make it much easier to find the device by looking for an LLDP neighbor instead of tracing MAC addresses.
I use to think the same thing, why don't they just have LLDP enabled by default. It would be very helpful in locating an AP's switch port!
I've since learned of the security issues associated with having LLDP enabled on both switching and AP infrastructure. I suspect due to the security issues Aerohive do not want to have LLDP enabled by default.