Can white do better versus the Sicilian Defense by avoiding an early d4? Given that 1.d4 is said to produce better results than 1.e4 and about half of all 1.e4 games involve the Sicilian Defense, could a simple idea like avoiding trading the d pawn for black's c pawn in the Sicilian be used to produce better 1.e4 results?  Perhaps after 20 or 30 moves the d pawn will come in handy after all!
All the main lines against the Sicilian are the open Sicilian.  This opening of the center gives white better attacking chances against black's lack of development.

Larsen claims that playing d4 is a positional mistake, allowing black to exchange a less valuable wing pawn for a center pawn.

Spassky played the closed Sicilian with great results.  And there are many anti-Sicilians which claims to give white the advantage.  The Grand Prix is the most fun, but I personally prefer the KIA.

The main difference between the open and closed Sicilians is the number of moves before the attacking begins.  The open offers more tactics right from the start.  The closed allows both players to finish developing before any attack really develops.

The real answer is that neither is necessarily good for white.  Since every line of the Sicilian is so heavily analyzed, the advantage goes to the player with the better knowledge and comfort in the positions.