What is so crazy about it? Standard American football rules allow for 4 attempts to get 10 yards, yet for some reason probably 98% of the time teams give up after 3. That is crazy.
The reason that most teams don't go for it on 4th down more (and TMQ points this out) is that most coaches would get blistered by fans, media, owners, etc. if they failed. It is easier to kick it away and then blame the players if you lose than to go for it, fail, and have to take responsibility for the call.
From one of TMQ's articles, here are his rules for going for it on 4th down:
• Inside your own 20, punt.
• From your 21 to 35, go for it on fourth-and-2 or less.
• From your 36 to midfield, go for it on fourth-and-3 or less.
• From the opposition 49 to opposition 30, go for it on fourth-and-4 or less.
• From the opposition 29 to opposition 3, go for it on fourth-and-3 or less.
• From the opposition 2 or 1, go for it.
• Exception: inside the opponent's 25, attempt a field goal if it's the fourth quarter and a field goal causes a tie or gives you the lead.