Probably because the Apple products to make use of it aren’t ready yet.
There are references in OS betas to assisted reality head-sets and a Tile competitor, which will both likely access this chip- but since they aren’t ready yet the demos for them were spiked and other references to the underlying tech scrubbed.
I'm guessing they won't release them until they have a new iPhone to try to sell.
It wouldn't really work if the new products only work with a product they released 6 months ago - there's little incentive not to just wait for the new phone anyway (Unless they expect everyone to be upgrading?).
No, because by the time they release anything the iPhone that was just released will be at least half a year old.
This might be a feature worth upgrading over, but who wants to upgrade in the middle of a cycle? The only people who would benefit are those who already have this new iPhone anyway.
So with all of these amazing attributes, why did Apple not announce the Apple A1 Chip? I assert it is a confluence of things:
The iPhoneOS software needed is not yet released
Apple will release AppleLocate tags for holiday shopping 2019
Apple had too many things to announce at this Apple Event and this would take too much time
Apple is aware of the privacy implication many will cast and wants to spend more time to explain
Other issues I can not present at this moment in time
