In every one of those systems, every ordinate is an angle, distances are space measure. It would be apples and oranges.

Another thing, locations on the sky can be determined to an extravagant degree of precision, for any object bright enough to be seen at all.

Distances, OTOH, are not known for most objects, and if known, only for those bodies which are easy to measure, and/or someone is particularly interested in and took the time to determine. They are generally known only to a very low level of precision (and are frequently updated as the state of the art improves). A +/- 10% error in distance is considered excellent in astronomy. Unlike angles, which can be measured to exquisite precision, distances are often only approximate.

As a rule, nearby objects' distances can be determined much easier and more precisely than more distant ones. For a location on the grid, distance is irrelevant. A distant galaxy's RA and Dec are just as precise as the closest star's.

It's sort of like the old sailing ship days, when a navigator could use his sextant to determine latitude to within a mile, but his longitude was purely an educated guess..