Are you sure about this?
Others on other forums have also indicated that there may be some EXIF data that can be read by the vendor s/w that are not sufficiently documented to include in the DNG converter. If you think this EXIF may be important, then this could be another reaon.
I thought that this undocumented EXIF (I assume the Makernote data) was extracted regardless of whether you embed the original, and that later versions of DNG converter may be able to extract some of this info. So this wouldn't be a reason for embedding.