Tolkien's 'Deus ex Machina'

[Lalwendë]

I agree the Eagles are a bit of a problem, but they still seem to 'fit' to me. They only appear at the most desperate of times, and sometimes not even then, and they only appear after great efforts have been made. Now I would separate The Hobbit out from this consideration as it was written as a children's story, and deus ex machina are to be expected (within reason, there's no need to resort to the 'pigwiggenry' that Tolkien so hated!), but in LotR, they may seem very jarring.

The other thing of course is that the Eagles appear when Gandalf is about, and both Gandalf and the Eagles are servants of Manwe. Though this is only something we would know by reading the Sil of course, maybe the fact that to readers of LotR there is internal consistency stems from the consistency to be found in Tolkien's greater work?