Hi Thadd,
I think, at a basic level, the original focus on Egypt came about because it is in Africa. Europeans couldn't explain an "advanced" ancient African culture as it didn't reflect their cultural stereotypes; in the C18 and C19 how could primitive Africa have produced the wonders of AE (and hence the dynastic Race throry - the same happens in India with the Aryan Invasion Theory). There's also the mirror image of this in hardcore Afrocentrist thinking. Those that believe that melanine in the skin somehow makes people superior have to explain why Africa was not the power house of civillisation and invention that China, India, Europe and South America were. To answer this the AEs had to be black Africans (and the Olmecs, and in some case some Chinese and Indians).
Effectively, I believe that the roots of the alternative fascination with Egypt (and I'm not saying that, for most, it is the current reason) lie in racist perceptions of Africa and Africans.
Pete
God is our guide! from field, from wave, From plough, from anvil, and from loom; We come, our country's rights to save, And speak a tyrant faction's doom: We raise the watch-word liberty; We will, we will,we will be free!