The notion that tilling the soil is necessary, or much less even beneficial, is totally bogus! The very idea is absolutely ludicrous!!!
Men bonded together centuries ago to create and perpetuate this myth as a method to spend all of their daylight hours walking around in fields behind an animal dragging a stick stuck in the ground (until the invention of the plow, and then the invention of the tractor) so they could spend as little time with their wives as possible. These days, farmers spend massive amounts of money on tractors, and the fuel to run them, for the same purpose.
Yes, suzi - DH is right. Not only does tilling the soil make it less dense so the roots your plants produce have less resistance to their growth - the voids (air pockets) created in the soil contain water better than in compacted (not tilled) soil.