The camera was not a priority for this mission. The small monitor camera was built and installed on the spacecraft thanks to public donations. This mission is about chemical and physical properties of the asteroid. Having a camera on it is mainly for publicity. NASA did a similar thing with the Juno spacecraft, letting people vote on where to point the camera while the main mission was to map out Jupiter's magnetic and radiation fields.
Indeed, none of these cameras need to be super crisp, although DCAM-3 (the deployable camera) is both a navigational tool and expected to provide some scientific insight. It was used to monitor the impact from the crater they created for the next sample, while Hayabusa 2 was safely on the other side of the asteroid: https://twitter.com/haya2e_jaxa/status/1114112619844005889?l.... That thread also has a shot from one of their navigation cameras, which apparently has a flash.
I love how many deployable objects this spacecraft is carrying, the target markers included. The number of moving parts must be staggering! (I wonder if they charge over USB? :b). JAXA has really amazed me with how resilient their missions have been. (The first Hayabusa limped back with a sample after a bunch of engine failures; their Venus probe failed to enter Venus's orbit, spent 5 years orbiting the sun, then tried again and worked). There's clearly a mountain of potential over there, so it's a treat to see this one go so perfectly smoothly :)
