A few threads deal with negative conversion
- Automatic negative conversion
- DXO Photo Lab works great with color negative scans
- Negative Conversion
- Invert film negativ in DPL 3
I think that DxO does have the brains to incorporate smart negative conversion, but maybe the market is simply too small to make it worth the effort.
Even if we had a good negative converter, restoring images gets down to fixing dirt spots, scratches and colour shifts due to faded dyes etc. 