Why is gasoline (octane) better than diesal (cetane)?

2 answers

Huh - who says?

diesel is usually ignited (except when starting cold) by the increase in pressure and temperature resulting from compression in the cylinder. Gasoline generally requires a spark plug. (unless the cylinder or deposits in the cylinder get so hot they ignite before the spark which is terrible for the engine)
http://www.scribd.com/doc/7292781/Differences-Between-Octane-Number-and-Cetane-Number#scribd
better? That is debatable.
diesel does not have to be refined as much.

Diesel is not likely to explode as easily. Gasoline has a higher vapor pressure, so ignites easier than diesel.

Why is gasoline "better" than diesel? Depends on one's viewpoint and use.