Given that Wonder Woman's physical durability was portrayed as being almost on par with Superman's at times in the cartoon, I'm not sure why she bothered blocking bullets at all.
Otherwise, I kinda suspect that Superman could have knocked out some of problems that the rest of the JLU was spending weeks trying to fix in just a couple of hours, but let them have their victories as a confidence builder so they'd be more effective when he actually needed them.
wish I had that image of this mock up comic showing superman asking her why she did that while they where both being shot at. she quit for a second and the bullets started bouncing off her tits which caused them to bounce, the criminals started giggling and wonder woman just glared at superman to which he replied "noted" or something along those lines
