Arguments to keeping the empty box:
"I kept the box to return it." Is it past the return policy? Used it, liked it, already sold it in last year's yard sale? Recycle it.
"I need it to sell it." Great! Sell it now--stop procrastinating.
"I need them for my next move." If you aren't planning on moving within the upcoming 6 months (and that's already half a year that boxes are consuming your space) post an ad on Craigslist or Freecycle.org--"Free Moving Boxes for Pick-Up, On Curb of [address]." You can post on Craigslist and go to grocery/department stores for stacks of free boxes when you ARE ready to move. It's not hard to find free boxes--trust me, I'm the queen of moving.
Boxes usually aren't the best things to organize things in. Clear containers with lids are better.