One of my favorite words is "vestigial." I find myself using it almost every day. My staff will often here me say of something that's leftover from previous efforts, "Oh, that's just vestigial." What I mean by that, If I'm using the word correctly, is it was relevant at one time but now it's not.
I don't want to be dismissive of the past, but I think it's important to understand that it should be held onto like an egg. You don't want to grip it too tightly or the results are pretty messy. Conversely, if you grip it too loosely, you drop it and still have a mess to clean up.
Last night, I started looking through old photos. Sure, I saw our dog when she was a pup, I saw friends I've lost touch with and I saw myself, 30 lbs. lighter. I realized, hey, maybe I should be a little more disciplined about my diet and activity leve. I'm not pining for the past but the past reminded me of a lesson I had learned.
Brands have to do the same thing. Learn you lessons fast but move on. Occassionally get out the photo album and reflect but don't wallow.