In America, a cul de sac doesn't add "a whole new neighborhood". It adds 3-5 houses at he end of a road cause they added a 'bulb' on the end. My neighborhood has 4 of them. Basically it makes turning around in a dead end road easier. Most cul de sacs in America look like this:
http://www.citylab.com/design/2011/09/street-grids/124/
Cims have no trouble turning around at the end of a dead end road. If you want to add a "neighborhood" at the end of a dead end, I still say make a small loop, or (if you want more houses) just
extend the road. You'll get more houses with a loop, and yes, there's an intersection added. Is the problem with that is it doesn't 'look' right?
Hey, if some of you think cul de sacs are important enough for the developers to spend their time on them, fine. Personally, I wouldn't use them. I'd probably just end up tearing them out and destroying the houses later in order to expand the road anyway. But that's me.