Why did the author of Kindred find it necessary to use a modern narrator to tell the story instead of having it all set in the past?

One of the problems with
historical texts is that they are set in the past and are so physically removed from our own
time. Butler's choice of having a character who time travels from the present back to a time
when slavery was the norm forces both the narrator and us as readers to experience the violent
and shocking collision between the norms of our world today and the very different and
terrifying norms of America during slavery. This narrative choice means that we, just like the
narrator, are unable to sit back and experience the reality of slavery from the luxury of our
armchairs. The juxtaposition of the two very different worlds constantly reminds us of the brute
reality of slavery and does not allow us to detach ourselves from it. Butler's purpose in this
tremendous story is to above all force us to become involved in the gritty, harsh reality of
slavery, just as Dana is forced to become involved. Note what Dana says to Kevin about the way
that what happens forces her to become involved as she struggles to cling on to her moral and
ethical reasoning from the present:

You mightbe able to go
through this whole experience as an observer... I can understand that because most of the time,
I'm still an observer. It's protection. It's nineteen seventy-six shielding and cushioning
eighteen nineteen for me. But now and then... I can't maintain the distance. I'm drawn all the
way into eighteen nineteen, and I don't know what to do.

The author intends for us to not become observers, and to, like Dana, be drawn
completely into the narrative action. This of course forces us to appreciate the brute realities
of slavery in a way that is much more powerful precisely because of the collision and
juxtaposition of the two different time periods with their different views on humanity and
morals.