Вопрос неверно поставлен.
Правильнее было бы: "Почему в прошлом инопланетяне не скрывали своего присутствия в отличие от сегодняшнего дня?".
И ответ на него походу нужно бы искать в прошлом.

We weren't created to be slaves as Sumerian texts claim - they are a manipulation of of older texts to justify the slavery (as,  say, the Bible is a manipulation of Sumerian and Egyptien texts to suit the demands of the Hebrews; as are other texts or legends manipulated in the culture and folklore of many other peoples and civilizations).

Probably the conditions on Earth weren't very friendly for the aliens and they projected themselves in a suitable species.

Дэвид Уилкок слишко большой оптимист. Governments are not teams of nobelists, noblemen and saints  , more often they are gangs of brutal cheaters and manipulators - so Anunaki legend would serve them better.

Дэвид Уилкок предсказал, что 21.12.2012г произойдет Ракрытие - Правительства всех стрен объявят о своем сотрудничестве с инопланетянами. А у нас эти инопланетяне  - Грабовой и Левашов уже пытались стать Президентами РФ

Конечно здесь, возмите зеркало и увидите одного!

The Darwin theory states that humans evolved from higher primates, specifically chimpanzees. All higher primates have 48 chromosomes, 24 from the mother and 24 from the father. However oddly, humans have 46 chromosomes in total, 23 from each parent. But our genome contains around the same number of base pairs as the primates, which is 3 billion base pairs. So if two chromosomes are missing, how do we still have the same amount of base pairs in our genome?! Where did the two missing chromosomes go?
Well, this is where it gets ‘stranger than fiction’ as they say. The 2nd and 3rd primate chromosomes have been fused together in humans, which accounts for the missing chromosomes! The end of both chromosomes (2 and 3), have been cut, and then fused together in such a way that both chromosomes continue to function properly. This really is a miracle, but scientists simply say that this "fusing" occurs in other species, specifically in nearly all versions of domesticated plants and animals. But they fail to mention that this kind of chromosome fusing is never found in "natural" species of animals with no domesticated offshoots.
As if that wasn’t interesting enough alone, there is more. Nine of our other chromosomes are what we call ‘inverted’. This describes a segment of the chromosome that has been removed, flipped over end on end, and then reinserted back where the segment came from. But how do scientists explain this?? The problem is, they don’t. There are very few scientists who ever delve into this. Perhaps they are afraid of what it means?

Another very important thing to mention, is that that there are 25,000 genes in our chromosomes, but 223 of them are not found in any other species on this planet! If the Darwin theory is correct and we evolved from primates, where did we get those 223 "alien" genes? Scientists try to explain this one away by saying our ancient ancestors may have been infected with bacteria and viruses that attacked us and nothing else on Earth, and then for some reason went extinct???, leaving their traces in us!?

Кто кандидат-архитекты нашего вида (пожалуйста, это не анунаки, эсли они действительно существовали, то приехали поздно когда люди уже были engineered)

1. Марсианы - узнав об предстоящию катастрофу, переселились на Земле

2. Другая, более развитая цивилизация -  arrived together with the Moon which might be a small artifial planet - spaceship.

3. Другая сверх-развитая цивилизация, которая пользувала запис своего ДНК on the primates. Travels through spaceholes.

Да здесь они давным давно. Мы сами их от себя скрываем.

Ну и чтоН Ну узнали о нас инопланетяне? Ну представьте что вы с другой планеты? Что, сразу будете лезть, обниматься? Сначала нужно посмотреть, определиться.

Другой вариант - что мы их не замечаем. Как пчелы, муравьи - человека.