This is clearly in the conditions Daloosh put in the 2nd post. Bolding mine.
Originally Posted by
daloosh
Restrictions that apply to the carriage of this smart baggage. Specifically that:
- Customers checking a smart bag with a removable lithium-ion battery must remove it and take it with them into the cabin. Customers carrying-on a smart bag containing a removable lithium-ion battery must remove it from the designed enclosure prior to boarding the aircraft. Once the battery is removed from the bag’s designed enclosure, the battery may be placed inside the carry-on bag. The removable battery does not need to be carried separately from the smart baggage.
And advisory:
https://www.delta.com/us/en/advisori...-bags-advisory
This is a simple reading of the rules.
As to why, I would guess because these batteries are going to be somewhere on the outside of the suitcase shell and therefore are vulnerable to all the squishing, collisions, and abuse bags take. They've decided to not trust any manufacturer to armor the batteries.