Tut died/was killed in his late teens, I think. He had no time to arrange his eternal resting place. They had to put something together in a hurry. Then there was apparently a small scale tomb robbery, and they sealed it up again. Before they could go back and do anything more appropriate, the large deposition of flood debris covered it up possibly within the same year. I have read elsewhere that Horemheb, the next ruler may have had it in for the family, and who knows how busy they may have been struggling with one another. It’s not like they could just get a few moving trucks and cars and run out there to fix things. Planning had to be fairly elaborate and subject to who knows what scheming and sabotage. OK, I found a link, Horemheb, commander of the Army was in Asia (probably meant the Middle East) when Tut died. Ay, Tut’s vizier took over for 4 years. The kingdom had been in a state of turmoil for a while because of Akenaten’s radical “one god” changes and new city of Amarna. The priests of Amen fought this and when Horemheb came back several years later kicked Ay out and tried to erase his memorials. See this interesting article for all the complicated details:
https://en.wikipedia.org/wiki/Horemheb
Nope, no flood deposit.
Horemheb didn’t succeed Ai. He lived over a century later. There’s a complete blank regarding his origin or details of his life, until he came to power, so there has been an invention of a former career. He was a viceroy, ruling over Egypt under the Assyrian king, and the Assyrian period followed the Ethiopian or Nubian dynasty.
The 18th Dynasty died out (the Amarna period was a pretty nasty denouement),
http://www.varchive.org/tac/seqdyn.htm
> The so-called Nineteenth Dynasty will be found to have been displaced not only by the five hundred and forty years of error in the dating of the Eighteenth Dynasty, but also by an additional one hundred and seventy years — the duration of the Libyan and Ethiopian dominations over Egypt: and the total error will be found reaching the huge figure of seven hundred years.
http://www.freerepublic.com/focus/news/1774343/posts
> four blue-glazed jars [the pharaoh’s canopic jars, from his tomb] bearing the nametag [cartouche] of Rameses II (1302-1213 B.C.)... actually contained an aromatic salve, while a second jar held the organs of an entirely different person who lived around 760 years later.
— nearly 800 years, which is the figure V derived by the time “Ramses II and His Time” was published. RC dating has always supported his chronology and has so undermined the conventional pseudochronology that it has led Zahi “Zowie” Hawass to claim that RC dating “doesn’t work” in Egypt.
Regarding the Aten -- the religious schism (which was of starkly political character) had started up a few generations before Akhenaten, revived from Old Kingdom practice, then brought to supremacy. Tut was involved in a power struggle, changed his name to the one familiar today (had been Tutanhkaten), then restored the older temples. Egypt's commoners had been unable to worship in the shuttered state cult centers for years. Despite a short reign, Tut erected a large colonnade; Ramses II later had his own name carved over Tut's, but up near the former ceiling, where no one would notice, Tut's name survived. Ramses "the Great" was a self-aggrandizing punk, btw.