I'm not entirely sure why it is that the Galochio's are always told and the Aquato's aren't. Generally I think this just makes it so the author can have a super awesome scene where the Galochio reveals everything, it makes for a good plot device. Even so, it depends on the fic and the reasoning behind it. I mean, in my fic...things are a bit different, since in the Galochios case it's been their duty to stop the Aquatos for generations Originally the Aquatos were the "bad guys", after all, and it was the Galochios duty to stop them...thus, the Galochios were extremely strict, because...well, they had to be. If they weren't strict, the one who's next in line for carrying out the fight may fail, and they couldn't have that. As time went on that power started corrupting them and those feelings of hatred that were instilled from the beginning grew and grew, twisting into this...obsessive near-insanity that got passed on and on, and of course the Aquatos only made it worse, seeing how at the time they were the evil ones.
By the time the Aquatos came to their senses, the Galochios were far too fixated on the whole "Must-stop-Aquato-and-save-world-OMG-HATE!" thing to stop. The Galochios have gotten to the point where they're all pretty much crazy and obsessed with that one single thing. It's pretty much all they'd tell their kids about, so their kids know what "OMG THE AQUATO'S DID!!!11oneone" and how "OMG YOU NEED TO KILL THEM ALL!" Meanwhile, the Aquatos...have really realized "Well crap, we've been idiots and now those guys who have been trying to stop us are just as psycho as we were." They can't talk the Galochios out of it because they're too far gone to listen, so they take a slightly cowardly route and just try to forget the problem. Pretend it's not there, hope the Galochios insanity will kill themselves off, and maybe it'll all just go away...yeah, that didn't work. Now finally we reach Nereus, whom has...pretty much taken what was originally the Aquato's role, and Raz...well, he's got to work out how to end this whole mess.
...but that's just my story. I really can't say why in...just about all A vs. G fics the Galochios are the bad guys (mind you, in CP they weren't originally, but that whole mess kind of works in this weird twisted circle, so...). I think it's just sort of the default black and white mentality, Raz is the good guy and the Galochios cursed his family so obviously they must be the bad guys. Raz's family is strict but caring, so to go with the opposing forces thing the Galochios must be a much of psychotic, abusive psychos. It makes an interesting contrast, I suppose...that and it makes a good plot device, which is what I think most people are looking for. But I have seen fics with good Galochio's in them. Take a look at Cursed (
http://www.fanfiction.net/s/2773209/1/), wherein the main OC is a Galochio, and her family is most definitely not portrayed as a bunch of psychos. Also, there's Noz from King of Fools (
http://www.fanfiction.net/s/3102325/1/)...granted), the Galochios are still pretty crazy here, but there's more to it than just "lawl teh Galochios are teh bad guys!!111".
It's not like it's necessarily a bad thing to have the Galochio's as the bad guys, either. No, the game didn't say they were a bunch of abusive psychos and they're all OMG EVIL, but it didn't exactly say they were a kind, caring, loving family either. Aside from the naming of the Hand of Galochio, Raz's mentioning of the curse, and the posters in Raz's mind, there's no canon mention of them. This means really, they can be taken and interpreted as the fic author sees fit...it just so happens they tend to be interpreted more as villians, that's all.