Nope, cause we have JLU for the excess of heroes.
Quite frankly, the ones you mentioned:
Nightwing, Robin, Batgirl = all humans, and
Batman's basically the most fine-tuned "human" on earth, so to have his partners fight against aliens would be suicide
Supergirl =
Superman probably didn't want her interfering
Static & Gear = probably percieved as being "too young"
Aquaman = doesn't care about the rest of the world
Who's to say that Starcrossed's events didn't spur on the JL's decision to expand? With all communications probably being monitored, the JL couldn't exactly just go and contact anyone they wanted--the Thanagarians had a lock-down in effect. Superheroe's probably stayed in their hometowns to protect against the bird-men.
This is all theoretical, but it's the best reason I can come up with. Too many heroes would've taken away from the impact of the Hawkgirl/GL relationship.
-BB
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