Is an infant seat really necessary?

ally2011

Sorry ladies to double post on car seats, but I have one more question for STMs....is an infant seat REALLY necessary or can I make due without one and use a convertible from the start.  I want to baby wear as much as I can because I hate lugging stuff around, strollers, etc....though I know there are times when I will want to have a carrier and a stroller.  But how often is that, really?  I know you aren't supposed to wake a sleeping baby, but if she were sleeping when I brought her home, I would move her to her bassinet as I thought you weren't supposed to let them sleep forever in car seat anyway.  And if we were out, in theory wouldn't she settle back down once in a wrap or whatever?

I know this all might sound naive, I just hate the idea of buying such a big hunk of plastic that will be used for such a short amount of time before needing to be in a convertible seat anyway.  

Thanks for any advice.