nikkaz sometimes forget the importance of the punting team in the NFL and like to be on that Madden "I always go for it on 4th so I don't waste the down" steez. This can fly in the HS level especially if you got talent more stacked towards the offense.
But in the NFL, a well placed punt that puts the opposing offense deep within the 10yd line can be the factor that keeps the opposition from nickel n diming you with field goals or even getting an easier track to a TD.
Also, going for it is essentially high stakes gambling in the pros. For those times a quick first down can be grabbed, there are times it can just be

. If an NFL team is going to start a drive close to midfield, I'd rather it be because of an amazing return, not because I just gave it to them.
Look at the overtime between the Bengals and the Ravens. Going for it on 4th down instead of pinning the Ravens ofense back trying for a stop, and getting back short yardage for a FG win?
Marvin,

.
Of course, there are a few exceptions, like the obvious 4th-n-inches stuations and when you are down by 3 scores in the beginning of the second quarter.
So like I said, if a coach can recognize where the talent lies in a Pop-Warner or HS situation, then by all means, do your thing, but pro coaches trust their punters as actual factors in game management, and trust their well-trained defenses to make the stops for them.