All the maps needs to be set up to fit with newer updates. Some items on the map is placed with code, cameras, fire-hydrants and chemical tables for example. All of these needs to be changed for the older maps.
If you have opinions about any aspect of any of these maps (especially things you liked and would like brought back), I would encourage you to use the map suggestions section
I seriously don't understand the hatred towards V4. V1 Office is back (which many people liked) and Projex made a comeback which was very widely used whilst server population was up
@LEWIS 088 Even if we bought back the old map, it won't bring back all 4 owners as well as the consistent supply of new players daily who stick around.