[Legate of Amon Lanc]

Originally Posted by radagastly

Natural disasters are only disasters from a human (or elvish) perspective. They have nothing to do with the (ongoing) shaping of Arda, marred or unmarred. We simply find them in our way!

Well, that's surely a good point. However, there is one thing - it's important to remember that Arda was supposed to be made for the Children to abide in it. I think part of the solution lays in what you hinted at earlier, that the Valar did not originally think of the Elves and Men coming in the world.

Originally Posted by Ainulindalë

And they saw with amazement the coming of the Children of Ilúvatar, and the habitation that was prepared for them; and they perceived that they themselves in the labour of their music had been busy with the preparation of this dwelling, and yet knew not that it had any purpose beyond its own beauty.

(emphasise mine)
In other words, for example Aulë could have thought that an erupting volcano could be a nice thing to behold, but did not think of the possibility that it may harm anyone. However...

...however, I am sure that's not satisfactory explanation. First, even my example above is probably a little bit "out", since we know that Melkor created the "unbearable heat" and so on, so generally, I daresay that probably even then Valar did not originally create anything "harmful" by itself, that it all came through Melkor. Then, many beautiful things (like the snow etc) came out of originally evil intention; but not vice versa.

And concerning my volcano example, it was just an example - probably a bad one, by the way, because

Originally Posted by Ainulindalë

Melkor too was there from the first, and he meddled in all that was done, turning it if he might to his own desires and purposes; and he kindled great fires

So who knows if it's even a good example

Also, when Valar came down to Arda, they had still much, much work to do (and from that time comes what you, radagastly, mention in the second quote in your post above). The important thing is that they already knew that there were some Children coming - they knew it from the Vision, and they were technically making the whole World anew, just "by the lines" of the Music. Let's see:

Originally Posted by Ainulindalë

But when the Valar entered into Eä they were at first astounded and at a loss, for it was as if naught was yet made which they had seen in vision, and all was but on point to begin and yet unshaped, and it was dark. For the Great Music had been but the growth and flowering of thought in the Tuneless Halls, and the Vision only a foreshowing; but now they had entered in at the beginning of Time, and the Valar perceived that the World had been but foreshadowed and foresung, and they must achieve it. So began their great labours in wastes unmeasured and unexplored, and in ages uncounted and forgotten, until in the Deeps of Time and in the midst of the vast halls of Eä there came to be that hour and that place where was made the habitation of the Children of Ilúvatar.

So, at that time they already knew that there will be some Children, and they surely tried to minimalise the danger for them. We are told that even in connection to Melkor:

Originally Posted by Ainulindalë

And [Melkor] feigned, even to himself at first, that he desired to go thither and order all things for the good of the Children of Ilúvatar, controlling the turmoils of the heat and the cold that had come to pass through him.

There are two things I would conclude from this part:

1. Even Melkor wanted to (or pretended to want to) control the bad things he created. So it's I think safe to assume that the more the other Valar would want to calm down any harmful things they made, now that they knew that the World was made for the Children to live in, and not just for itself. (If ever the other Valar made such things, as I hinted at earlier, and also see below).
2. "That came to pass through him" - this sentence can mean two things. Either, Melkor wanted to control just the heat&cold HE created and if any other Vala made anything harmful, he did not care but wanted to undo just what he did. This would mean not just hot&cold, because I am sure Melkor made more "harmful" things than just the heat and cold and that the heat and cold are here named just as examples representing all Melkor's dischord. So, it would mean "Melkor wanted to undo what he did, but if any other Vala did anything bad as well, he left it to him". After all, why not. However, there is second explanation possible. If we put the main point in the words "that came through him", we could understand the sentence as "He wanted to undo all the evil things, that all came from him." I hope it's understandable - I mean that it could mean that all the evil came from Melkor and from no one else. This idea is supported by the fact that in the Music, everything went fine, and apart from Melkor, there was no dischord, even when the third theme (the one CONTAINING the idea of Children) came.

Then there is one last thing, which supports the idea that the natural disasters are "evil" in nature. As I said just now, there was no dischord between the Valar, apart from the one Melkor created. Even in the beginning. And here is my point. Yavanna, as we know, created kelvar and olvar (animals and plants), and as alatar already said in his first post, Yavanna would surely not be happy with the uprooted trees after a wind storm. But there was nothing like Yavanna's sadness at first in the song, so we can conclude that Manwë did not create any sort fo wind that would tear trees from their places. And the most important, and with that I am going to finish, is the animals. You said, radagastly, "If a tree fals in the forest, and there's nobody around to hear it, does it make a sound?" It's appropriate to say that if there were no Children, the natural disasters won't need to be classificated as "bad" because they won't harm anyone. But let's not forget that even before the Children, there were the living plants and also animals who can be afraid of things, and you'd hear them screaming if suddenly a volcano erupted near them. In this point of view, the original, unmarred Arda without Melkor would have been unharmful to its denizens, be they the Children or just plants and animals.