Well, I certaintly hope that its ok... otherwise I don't know what I'm going to do when I have 2+ kids one day.
As of right now, I only have one DC.. and while he's almost 2yo, he weighs under 20 pounds. So its sooooo much easier to just stick him on my back than lug around a stroller. I especially love wearing him while grocery shopping because I can abandoned my cart to run down an aisle to grab one thing and I get my shopping done faster.
I agree with the PP though - I hate seeing the teeny newborns in the "travel systems" constantly. I was talking to a mom in the waiting room where DS goes to therapy and her newborn DD was in one of those things (ya know, in the infant carseat, on top of the stroller). I mean, why go through the trouble? She lugged out an infant seat and a stroller to walk literally about 20 feet and then park her baby instead of just carrying her in? Now that doesn't make any sense to me. If I had passed her in a store or on the street, I wouldn't have thought anything of it... But this mama was using the stroller as a baby holder, not to stroll.