Brian Green on the Large Hadron Collider

In writing about the possibility that the LHC might produce black holes that would eat the planet, Brian Green wrote,

Work that made Stephen Hawking famous establishes that tiny black holes would disintegrate in a minuscule fraction of a second, long enough for physicists to reap the benefits of having produced them, but short enough to avoid their wreacking any havoc.

Even so, some have worried further that maybe Dr. Hawking was wrong and such black holes don’t disintegrate. Are we willing to bet the fate of the planet on an untested insight? And that question takes us to the crux of the matter: the collisions at the Large Hadron Collider have never before occurred under laboratory settings, but they’ve been taking place throughout the universe — even here on earth — for billions of years.

Cosmic rays — particles wafting through space — constantly rain down on the earth, the other planets and the wealth of stars scattered throughout the galaxy, with energies far in excess of those attainable by the Large Hadron Collider. And since these more powerful collisions haven’t resulted in astrophysical calamities, the collider’s comparatively tame collisions most assuredly won’t either.

I'm not one of those opposed to turning on the LHC. What I don't understand, though, is why we need it if the collisions it will produce are already plentiful on earth.