Thank you for yout thoughts on this topic. I agree with you in most aspects.
It is a very interesting issue to think about what are assumptions and what are not, and how much we are biased by our cognitive preconceptions. Orthodox researchers may say that alternative authors are biased by their 20th or 21st century minds, or way of thinking and understanding the world. We have to suppose that ancient cultures had a different way to understand Nature or Universe.
And that's correct in my opinion, but... leaving behind the beliefs, it's obvious that the evidences are there (pyramids, sphinx, etc.), and we have to look for the correct interpretation of them. And that's the key: Ancient Egypt is somehow a strange culture to us, we are not able to understand properly the root of their beliefs, their complex religion and spirituality.
We are too rational, too materialistic to break the rules and make a new proposal (perhaps Schwaller de Lubicz's and West's works are a first step in this direction). Orthodox science deny the very ancient dating of pre-dynastic kings (gods, semshu-Hor, etc) but they are there, we cannot pretend they were mere fantasy (or can we?). We must study all the likely scenarios, gather data and analize the evidence to make new hypothesis. No matter if we make mistakes, that's a part of the game we have to accept.
I am not defending the actual existence of a lost culture (Atlantis or whatever you call it) or an alien intervention, but I will defend the need for a serious debate involving all the visions and a multidisciplinar approach about some phenomena which aim to a different comprehension of our remote past. It is useless, in my opinion, to create "trenches": we all ought to have a free spirit to discuss in order to increase our common knowledge.
The problem is the following: one side considers the other side as a sort of commercial nonsense, and the other side considers the first one as an intellectual fortress, keeper of dogma. By the way, has anyone mentioned before the word "taboo"?
Veritas ipsam viam inveniet