What Are The Motives For The Following Dungeons?

Title says it all
1. Lost Sanctuary (I mean, Garoth is being much of a problem)
2. Underworld Crypt (Why though? Does Graken want revenge for all the lives lost during the attack on Ancient Nemract?)
3. Sand Swept Tomb (Pretty sure Hashr is stuck in there, there's no way he could get out)
4. Ice Barrows (Same reasons as SST and LS)
5. Galleon's Graveyard (I remember something about a treasure, but at the end of the dungeon you end up with no treasure whatsoever)

 

So basically every single (non-corrupted) dungeon

 

1. Mage Island wants us to access Garoth (I think)
2. Charon still poses a threat (I think)
3. Lanu opened the tomb, and we're trying to stop Hashr from escaping and destroying everything
4. In the Fate of the Fallen quest, Theorick asks you to "end it all"
5. Redbeard is still terrorizing the seas (I think)

 

I mean, leaving a known enemy that can and already has destroyed the city nearby literally right on your doorstep isn't exactly a great idea, not even mentioning the fact that zombies are coming out of it, making Ancient Nemract uninhabitable. Basically, in a fantasy world where you could only do Dungeons once and Wynncraft was real life instead of a game, after you defeated Underworld Crypt, Ancient Nemract would be safe to AFK in, since zombies wouldn't be coming out of the skull anymore.

 

Can't answer for Galleon's graveyard, but:
Garoth is amassing an army of creatures
Hashr was so powerful that the only way they could stop him was seal him in a tomb, and he's still going strong
Charon took out Ancient Nemract, may move again
Thoerick asks you to take him out
The Characters in Redbeards booty brought Redbeard back to life and joined his crew so they could terrorize the seas with him

 

About LS, I think that Garoth was working on a cure for the corruption, or just had an immense knowledge of the corruption, but Mage Island didn't know that he was corrupted, so they were trying to get to him and ask him stuff