Uncrewed space station should provide some research/unity boost

Space station I is uncrewed and provides a small unity/research boost, so why shouldn't space station II and higher at least provide the same as I did even when uncrewed? Ideally still slightly higher at the higher levels (maybe equal at II, then slightly higher at III+).

There's plenty of times you might not need space research but be faced with either shutting down the station (and paying the parts upkeep), leaving it working and paying the cost for crew and supplies (which is mostly painful on the crew launches), or downgrading the station to a I until you eventually need space science again for the repeatable researches etc.

Logically I would expect the station might need some occasional crew for maintenance once it's sufficiently advanced, but having it fully shut down just because there is no crew is what seems a bit odd. I would think there should still be some functions that could be accomplished while it's empty that would be equivalent to the initial unmanned station.