They don't owe humanity anything, but they need to get back into their good graces and prove they can be trusted to have a nation again. The last time humanity gave the elves a nation, the elves invaded humanity with it.
What is given can be taken away.
Indeed, this was the problem with the Dales. It was given to them by humans - and then it was taken away from them once it became inconvenient. It was inevitable and they should have seen it coming. Maybe they did. Could explain why they reacted with such aggression to Orlais' provocations. They just wanted to live in peace, but the humans would not let them be. Maybe some of them wanted war... foolish young warriors to settle past insults. There is a lot of bad blood between humans and elves. And it continues to this day... that is not a problem that will be resolved peacefully. There can be no peace without justice. No compromise.
"In time, the human empires will crumble. Until then, we wait..."
So they wait. Next time they will not ask the humans for a permission to have their own nation - they will simply take it. They will not make the same mistake twice.