For people like me that never get near shops to buy things in the day and only have places like tescos or sainsburys open when I'm not at work places like Amazon are useful.
They also seems to be getting more and more useful as the proceed to open more and more stores, it used to be just books but now you can get your books, dvd's, games, appliances, clothing, watches, shoes, and now according to their front page Babies. Now I take no judgement at their move into child trafficking it might be useful some day if I need some stem cells or a handy distraction in a fight or something.
It does seem like they are becoming a one stop shop for anything you could want, the US version has started selling food as well, how long before we too can get our groceries at amazon along with a new fridge freezer to keep them in.
Still unlike their meat space competitors in the sell everything that's not nailed down market, they repeatedly struggle to turn a profit despite huge turn over. I guess the fact they work on such slim margins that makes their stuff so attractive to joe "skinflint" public doesn't make for a very profitable business.
Maybe they need to branch out into the real world start shops where they sell the same stuff at a small premium