It may be the essence of humanity but it's not human. Therefore, I think it's missing the point what it wants to actually preserve.
Even then, the notion that the "essence" is preserved just seems like vague BS they (Bioware/starchild) say that isn't substantiated in any way. Reapers are just made from organics in some weird way. Humans are nothing like reapers. No organics seem to be. I mean, effectively every non-indoctrinated organic has loathed the very concept of Reapers and what they do, yet no Reapers appear to have any qualms with their task once they're Reperized. I have absolutely no idea how anything is even remotely perserved. At best they have a DNA imprint for historical logs. Whoopidy doo!