When it comes down to it, I say y'all are right, but it is interesting to play around with in fanart and fanfics. Afterall, if fans of other fandoms can slap together pairings for online entertainment, why not this 'n? I know I do it.
I don't really take any non-canon pairing die-hard serious 'cause if the writers of that particular show (comic, movie, whatever) didn't place 'em together, then it's just some fangirl's or fanboy's lil' fantasy. Oh, the fights that evolve from such questions and comments amongst fans.
I know the Teen Titans scene is horrible with the Raven and Terra shippers for who gets BeastBoy amongst other pairings. But yeah, rambling off here.
Anyhow, I think the writers may actually hint at such possibilities in the show (as with any other nowadays) for the fanpeeps to write and draw about, but for the intent for the show itself, they are more-than-less just sibling-type friends.