In terms of home use 16GB is only going to come in useful doing heavily layered photoshop (100's high res layers or panoramic stitching), similarly complex HD video editing/rendering or VMs as mentioned.
I use a rig with 48GB of RAM and it is fairly easy to hit this RAM limit, we could use 96GB+ but its not worth the outlay. Its used in volume mesh generation for CFD analysis if you were wondering. CFD workstations with 192GB of RAM are not unheard of and the clusters that the simulation is run on can have TBs of RAM available over the nodes. The very top end hardware nodes can each have 512GB RAM on board.