If it was the correct brightness you wouldn't have to get used to it.
I am also talking about using it in a totally dark room.
I have been using a Kobo Touch with a small clip on light for some time and, although that was not quite bright enough it was a lot more restful on the eyes. I chose the eInk screen devices as I didn't want a bright screen as on the colour devices available.
Having said all that I do find it less objectionable now than when I first got it. It is not a case of advancing technologies I am sure it is a simple case of a tweak in the software to give a wider range, leaving the brightest setting as it is but allowing it to go dimmer.