The constraint with Mars is not the imaging capacity of the spacecraft, but the transmit/receive bandwidth from Mars orbit to the DSN (Deep Space network). Although newer craft in orbit have had higher power transmitters and better bandwidth, it is a lamentable reality that only a few % of the potential data that could be captured can actually be returned to Earth.

Strategies such as on-board compression of images can increase the data transmitted, but often at the expense of introducing artefacts and degrading the effective resolution of the cameras, so lossy compression is not preferred. Lossless compression has some value, but is limited in what can be acheived - a few times more data, not the orders of magnitude that one might ideally want.

Like yourself, I'd like to see detailed images of key gullies, especially those in the Sysyphi Cavi area where I beleive there are springtime flows. In time, these will come. Patience may be required, though...