These sort of plots are indeed exceptions, but that's what makes them interesting. And they are not possible if the monster isn't generally good. For example, one of the reason fallen Jedi are so cool (and they are, even after it has become a cliche) is because Jedi are paragons of goodness. In previous editions of D&D, this same trope could be applied to paladins, dragons, angels, and several other creatures. Now, it's more like "WTF is this gold dragon attacking us for??? Is it a freaky mystery? No, he probably just wants our treasure, or to manipulate our society somehow. Par for the course."
I agree that most of the monsters in the Monster Manual should be evil or unaligned or any alignment. But I think the game is more interesting if there are a handful of good creatures in there too, to use in exceptional circumstances. If I were the designers I would have drawn the line at unicorns and silver and gold dragons (copper and lesser metals never seemed that "good" to me in previous editions). That's like 10 stat blocks over the course of 2 books, so like less that 5% of the stat blocks going to seldom-used good creatures.
-- 77IM
Hmm . . . part of my argument was centered on the number of good creatures that would be in the book if all Metallics were good, so only having two good dragons might well deal with that problem.
As for your main point . . . actually, I still think there's some mystery associated with a gold dragon attacking (because they are unaligned, and not evil), but I can agree, its certainly less than if their alignment was good.
I agree with part of your argument about "fallen" creatures - I think fallen Paladins and fallen Angels both were cool, although overused, and the loss of an association with good has lessened that somewhat. I say somewhat because a Paladin of Gruumsch is still certain to raise eyebrows, and you could still have an Angel of Bahamut who latter goes rogue.
On the other hand, even metallic dragons are generally self-absorbed and have motives often not understood by lesser beings; a "fallen" Gold Dragon is neither particularly cool nor particularly uncommon, I think. To be honest, I think dragons are just not particularly well suited to the good alignment, for the arguments I mentioned above. I also feel the same way about unicorns - they're certainly not evil, but they are not so much paragons of good as paragons of the natural world, which are two very different things.
Needless to say, none of this has much to do with my original argument. Still, maybe there is something here about how I see alignment, and maybe it is a point others disagree with. Unaligned seems like the "default" alignment choice - as in every creature in the real world would be unaligned. Thus it seems reasonable that many creatures might be unaligned. I also have no problem with races that evil in alignment - either because they are creatures of elemental evil, or because their culture, like that of the Drow or Orcs, is one that encourages violence, savagery, etc. Good-aligned creatures, though . . . a culture that promotes "goodness" seems somewhat redundant, since that is generally the goal of all cultures, though they have little success; worst, taken to extremes, this can breed fanaticism. That leaves only races of elemental good - angels of good dieties, etc. And it's not a list I would expect to be very long at all.
"Unaligned" is a much better descriptor for this behavior IMO, so I definitely approve.
