Why do you think an Edit Mesh modifier would be superfluous? Edit mode is great. But what is greater is being able to quickly hide and show various edits made, and if the topology remains the same, even being able to remove several layers of edits.
Since so many people said this probably requires edits on the C side of the source, I understand the difficulties now.
BUT…I find myself so often saving multiple files to move backward, or using multiple layers to hide older edits of a mesh. The snapshot add-on seems like a perfectly good hack/work-around. But none of that really replaces storing the edits in the object data itself, being able to quickly hide and show edits, delete single or multiple edits at once (providing the topology remains the same), being able to change the topology at later stages in the stack (which of course, effectively renders that a new starting points, to return to an earlier state would undo the topology changes)…
But my original question…why do you consider this superfluous?
I have really come to enjoy the Blender workflow as compared to make, minus some things (object duplication and cloning, multiple duplications without making a full-on array, etc. Some of the tools mentioned here I never really used so I can’t comment on those).
But the Edit Mesh modifier is the single function I miss most. Why do you think it is superfluous?
(Now that I think about it…I wonder what happens if you stack up multi-res modifiers but don’t subdivide…simply edit within the modifier?)