I won't and honestly don't think anything needs to be done instead. I would change my mind if there was some serious trauma to the baby around day 4-6 after birth, but otherwise I honestly believe it is unnecessary.
The baby is born with stores of Vit. K from mom that slowly deplete over the first week of life and by day 8 they should be making their own (gotta love the Jewish tradition of bris on day 8 for falling so perfectly in line with nature on this one.) The idea of giving every baby Vit. K seems to be tied in with things like routine circumcision (in which case I would deem it necessary as this could potentially be done in the low-K window). A baby tucked safely into his/her mother's arms should be at little to no risk of bumps, bruises and cuts that could cause a problem in that small window when they may be low on K.
The funny thing is that I got all of my information convincing me of this from my husband's medical textbooks, which makes me wonder why so many doctors do it routinely in the first place???
I'm a pretty big believer that God created us to function without a lot of medical intervention and it seems a little off to me that babies need an artificial boost of vitamin K 100% of the time.
Edited because I just talked to my husband and he says the "low" window is day 3-7, not day 4-6. But that doesn't really change my thinking.