Capriati has a tendency not to attack second serves? Are you kidding me? That's her bread and butter.
I think players like Jennifer, Monica, Venus, Lindsay and Serena have strokes built for aggressive shots on the return. (Also Hingis as well)
Justine and Amelie are alike in their having bigger takebacks on their forehand, and single-handed backhands, so they tend not to go for so much on the return, but just to block back powerful first serves, or try to put a lot of spin on the second.
It's perfectly fine on the clay, but I do think it's a weakness on the hard courts and one reason why Justine has struggled on hard courts.
But she was probably smart not to go for it today. She didn't want to get too upset with herself for missing too many, so she played it safe, just tried to get through the first round.