Why would she be? She's "technically" part of the Superman family, but reality she's always had greater ties to JSA then any of the Superman cast.

" it would be fun too see her more in superman family actully :) "

" or maybe beguse she dosent have the S on the chest? "

" @WW-Fan said:

" or maybe beguse she dosent have the S on the chest? "

thats probabaly the reason, i'd like to see her in some of the Super titles "

She dosent have S on chest because there is no fabric on her chest.

For a while post-Crisis she had that retconned Atlantean origin. So she had quite a lot of appearances in the JLE, JSA, and various other books where she had been distanced from the Superman mythos. Even with her Kryptonian roots restored,  PG still has this independent persona so I think she doesn't spring to mind as quickly when writers are thinking of Superman Family members like the more overt Superboy and Supergirl do.

maybe if they put her giant cleavage hole in the shape of superman's shield she'd be in his books 

There's no S on her chest because that's where the hole where we can see her cleavage is. :P

Hmm she is the cousin of the Golden Age Superman right?

"Hmm she is the cousin of the Golden Age Superman right?"

" @Primmaster64 said:

"Hmm she is the cousin of the Golden Age Superman right?"

i think so! i read she is the golden age super-girl "

Why does she have such gargantuan tits is my question?

@Soloman:
she is an older version of kara... so what you should be asking is, when do kara tits get as big as power girls?