IBeacons interfacing directly to the hub wouldn’t be very productive, unless the hub was in a physical location where you wanted events to fire. Probably not usually the case. I think the same is true for many bluetooth devices. BT range isn’t that great. My ST hub is in my basement with my network, security panel, etc… bluetooth radio on the hub wouldn’t be very useful.
The point of an IBeacon is for a mobile device to see the beacon and report or do something via an app. IBeacons can provide better proximity detection than GPS, and they are often used inside a building where GPS is impractical.
IBeacon functionality would make more sense as part of the Smartthings mobile app, so that events could be generated as the person (phone) approaches a given Ibeacon. One at the front door, one in the bedroom, one in front of the TV and so on. A nice thing is that IBeacons aren’t permanently connected to a network. You can put one in your car, at your desk at work, etc. Your mobile app knows it’s in proximity to that beacon and could drive events through the system back home.