We could, but it’s way more expensive. There was a ~10m dish added to space VLBI, but the ground stations are several times larger, up to a few 100m. And you need dish size for sensitivity: in interferometry the largest distance between two telescopes gives the size of the synthetic instrument, but the size of the individual dishes fills up the detector.
Also, if something breaks it’s almost impossible to fix in space.
Why can’t we use the satellites for interferometry, too?
We could, but it’s way more expensive. There was a ~10m dish added to space VLBI, but the ground stations are several times larger, up to a few 100m. And you need dish size for sensitivity: in interferometry the largest distance between two telescopes gives the size of the synthetic instrument, but the size of the individual dishes fills up the detector.
Also, if something breaks it’s almost impossible to fix in space.