[Lalwendë]

I also find a problem in how Sauron got the Ring from Numenor. The answer to it could also lie in the nature of the Ring of course. But we do see one Maia without physical form and that's Saruman, and from the description of what happens to him, it wouldn't seem possible that he could interact with the physical world - after all, surely if he could, then wouldn't he have smote the Hobbits or somesuch? Instead he immediately appeals to the Valar and is rejected. Though perhaps this explains why they send the wind to dissipate him?

Now, there is another possibility as to why Sauron (and indeed Melkor) would want to take on a physical form. The possession of a Hroa actually provides some degree of 'protection', an additional barrier of Unwill to prevent the mind from being perceived. And if you have dark deeds in mind, then you do not want them to be revealed.

And yet more ideas... Of course Melkor and Sauron wanted to interact with the Elves, and then with Men and other mortals. Possession of a Hroa would instantly make this easier as a tangible person would be more readily accepted than a spirit. That's just simple psychology, and note also that both our Dark Lords also take on a 'fair' form at first, instantly attractive and appealing. There is also the issue of language, a pertinent one considering the central importance of language to our author. Incarnates have become users of language as habit instead of using sanwe, though Tolkien makes it clear they still have this ability, in some it lies latent and in others they do use it a little even when using language. Is it possible that it was essential to have a Hroa in order to use language?