Why do exoplanet researchers often measure orbital distance in AU around distant stars?
Answer
Because the governing physics (Kepler's laws) are mathematically identical to our solar system's scale.
Exoplanet researchers apply Kepler's laws, which are mathematically simplest when the primary distance unit matches the scale of the local system, even if the star system is light-years away.

Related Questions
Why is the Astronomical Unit (AU) preferred for measuring distances within the solar neighborhood?Which body formalized the exact definition of the Astronomical Unit and in what year?What is the current, precise value defined for one Astronomical Unit in meters?Before the modern formalization, how was the AU definition historically based?Approximately how many AU are equivalent to one light-year?Approximately how long does it take light to travel the distance of one AU (from the Sun to the Earth)?Why do exoplanet researchers often measure orbital distance in AU around distant stars?According to the table provided, what is Jupiter's approximate distance from the Sun in AU?How is the AU separation utilized when calculating communication delays for missions like those to Mars?What scientific advantage does the IAU fixing the AU value in meters provide for long-term planetary modeling?