First: We already have a command to copy rooms - rclone.
Usage: rclone <target room vnum>
You stand in a room and copy everything in it to a new vnum.
Now we don't really encourage repeated descs in 4D, but there are times when they are useful, for instance with mazes.
What I usually do when building myself, is making a room with the things I want to be generic for several rooms, for instance room name, roomflags, listen and smell descs, and if it's a maze the main desc too. Then I copy that room to as many vnums that I need, and edit the rest manually, usually with individual descs.
But for instance you always have to set the vnums of the exits manually, even though the exit descs can be the same.
What you suggest is a more detailed option, but basically the feature already exists and is in working order.
You'll have to chose whether you want to use buildwalk or rclone, however, personally I'd prefer rclone most of the time, but it depends on circumstances.