I agree with Joe. As he said, if you commit to diving and miss in this situation, the ball rolls clear into the corner, and by the time the center fielder retrieves the ball and throws it in, there are a LOT of extra bases.
There are things to consider: What is needed on this particular play? Is it "do or die time"? If the coaches mantra is "dive for every ball" your team is in for a lot of losses. Same deal if the coach says to never dive. What kind of teaching is that??
If you dive, is there a backup fielder? Like with a hit to right center, where the right fielder can curl behind for backup. I think in most cases there will (or should) be a backup fielder, except in those dead corners.
As kids get older, if they have played aggressive ball, they figure out what their range is. Diving "for diving's sake" is just plain stupid. It's similar to a great infielder knowing how to play a hop. They see the ball off the bat, and know when to charge, or let the ball hop. They play the ball, and don't let the ball play them. Nothing wrong with encouraging aggressive play, but not at the expense of SMART play. Knowing when the odds are in your favor you absolutely should make the dive.