I prefer a replaceable battery as well. That said, a replaceable battery is probably less important to the enterprise than a consumer. Enterprises will want to lock down, backup and secure phone data. Enterprises will issue dozens/hundreds/thousands of phones, and will have backups in stock. If a battery is going bad "IT" will load up and issue one of the back up phones.
I suspect that in a phone like this, space saving from eliminating the battery "packaging" allows a much higher capacity battery.
Until there is a teardown, we will nor know if these phones are serviceable; the battery may be replaceable by a technician.