Why did the Others leave Desmond in the Hatch?

[Hober Mallow]

Curiously, the Others didn't seem to realize Desmond failed to push the button when flight 815 crashed. And their reaction to the sky turning purple was a collective shrug. If they were watching Des, they weren't watching him very closely.

 

[Immolatus]

it really is just poor writing. I love the show and I'll watch it to the end. but really we will be left with a lot of questions.

 

[Mr Light]

Ah that's a good point. Since Richard met Losties from the future in 1953, he knew that nothing catastrophic would happen in between that time.

 

[Lindley]

They also knew where the Ajira flight would land, implying they knew the island would still be around in 2007.

No, they didn't know that. The only people from 2007 that the 77 Others met were Jack et. al., who were wisked off the plane before the forced landing, and thus couldn't have known where the plane landed.

The Others in 2007 knew where it landed because of their own recon, but that's all.

 

[Hober Mallow]

They also knew where the Ajira flight would land, implying they knew the island would still be around in 2007.

No, they didn't know that. The only people from 2007 that the 77 Others met were Jack et. al., who were wisked off the plane before the forced landing, and thus couldn't have known where the plane landed.

The Others in 2007 knew where it landed because of their own recon, but that's all.

I think what Delta is saying is that either they or Jacob knew where the Ajira flight would land because... well... it landed. The Others built a runway exactly where the Ajira flight would land, meaning they knew something was coming; or Jacob knew something was coming and the Others simply followed his orders and had the runway built. In any case, a plane was expected, a runway built, and the flight landed at that exact spot three years later.

 

[Mallet]

Also Illanya(?) and the other Jacob followers knew the flight was going to end up on the island. I'm pretty sure they wouldn't have gotten on the flight if they thought it was going to crash or that it had no where to land when it got there.

 

[Hober Mallow]

Actually, come to think of it, it's not even really a guess whether or not Jacob knew. Jacob told Hurley to get on that flight and that it would take him to the island.