Look at Ash at Wimbledon for example.
She was in great form coming into the tournament. She chose to take a last minute MD WC. She lost Rnd 1.
If she had played qualies, she would have won her 3 matches definately and may have even carried this into a MD win. I know winning isn't everything but Donna right now is not at the level to take that risk.
I think it's great Ash got the chance to play against Vinci. It is no certainty that a young player can win 3 rounds in qualies. In fact I was hopping she would get tough opponents in her GS 1st rounds, like the player ma re said. She also played against Kvitova. In the long run these are much better than facing challenger level scrubs in qualies, I mean you can just player challengers to play those people.
Look at Federer again, lost all his 4 GS matches in 1999. But it was valuable experience. In fact Roger lost twice in the 1st round of Wimbledon, before beating Sampras in 4th round in his 3rd try.
As I said winning isn't everything. I knew Donna had big potential even when she lost the final of $25k and everybody wrote her off.