In "Unimatrix Zero (element 1)", it was so the Doctor could observe her REM snooze and attempt to ease her nightmares about Unimatrix Zero. In "Imperfection", it was to keep track of the effectiveness of her malfunctioning cortical node. Given that Voyager was stranded in the Delta Quadrant as a consequence of Janeway's steps, regardless of what the reasons behind them, this could be a situation of her having "kicked upstairs.