The question then arises that if an X-Boat can be automated, why wouldn't the default model be designed to be automated, seeing as how you could replace all of the life support equipment and crew space with extra communication and data storage mission-module equipment (and avoid unnecessarily pressurizing the interior with an oxygen environment). A manned-variant could still be built for sensitive transmissions (to defend the vessel from boarders) and/or for transport of small high-value and/or sensitive express parcels (or passengers) along with the normal data-dump. But then maybe that is the only side of X-Boat Communications that we are seeing.
That brings up a point of Cart vs Horse ... ROUND 1 ...
FIGHT!
Designing an XBoat for automation isn't the issue (because it already is, by default).
You want to have quarters for up to 2 people on board so that the XBoat service can be used as an emergency transport system for highly sensitive cargoes and personnel (an example of vaccines is given in S7). By having habitable space aboard, the IISS can even use XBoats to move personnel around when issuing post reassignments and/or when mustering out of the service at the end of a career. Granted, an XBoat is no passenger liner, but it ought to be capable of carrying "precious" people and "precious" cargo (in limited quantities!) when needed ... in addition to the baseline capability of carrying communications between star systems.
Designing the system such that only "specialized" XBoats have the capacity to carry crew/passengers/cargo would be self defeating, since by their very rarity those "extra" transport services will always wind up being in short supply exactly when you need them (go away, Mr. Murphy!). The logistics of needing to manage two types of XBoats just isn't worth the expense of NOT having the capability to transport crew/passengers/cargo when you REALLY need to in a crisis situation. Better to just streamline everything on a standardized design that has the pressurized life support capacity built into it every single time so it's there whenever you might need it.
Because that's the thing about emergencies.
They rarely give you enough advance notice to get all your logistics "just so" and perfect in time to meet the needs of the emergency. Best to have the capacity built in from the start.
One of those "you always fight with the forces you have" kinds of deals, rather than wish casting for the forces you WISH you had to meet the moment.
I can easily imagine that there have been plenty of times (i.e. more than can be conveniently counted) in the history of the IISS between IY 800-1100 when the fact that the standard XBoat design is one that can carry a Middle Passenger plus 1 ton of Cargo has proved critically pivotal to the outcome of all kinds of time sensitive crises on plenty of worlds inside the Third Imperium. Even if it's a case of "1 world per year" out of the 11,000+ worlds within Imperial borders, that's still amounts to some 300 worlds that would have had a different outcome if the passenger+cargo option was not available in a time critical way during a world crisis.
Sure, it might cost a little extra relative to a purely automated drone service with no life support on board ... but when you measure that slight surcharge in XBoat fleet construction, operations and maintenance costs against the value of
WORLDS SAVED by having that otherwise superfluous capacity built into every XBoat, you're suddenly talking about shaving pennies at the expense of financial stability for entire banking systems.