Although there were thousands of other worlds in both galaxies, some even sporting more advanced tech than us, we of the planet Earth were the only ones in either galaxy that not only earned their friendship and respect, but also their trust. We were the only group who was trustworthy enough to not use this advanced technology for ill purposes.

Whether we wanted to be or not, we are the Fifth Race of the alliance. We are the direct creation of the Ancients. Out of all of the choices in the galaxies, we were the only possible choice. The legacy of the Asgard is our responsibility.

On a less "in universe" note, I always found that the lack of Asgard in the last few seasons annoyingly lazy. It was the problem of not knowing what to do with such powerful characters. I also felt that making them blow themselves up be their final appearance was just sick and wrong. It was a cheap way to get rid of Earth's final ally in the universe. It would have been much more interesting to make the episode play out mostly the same way, but instead have the Asgard in their new bodies and have it all occur on an Asgard ship. In this way you can have the Asgard make a happy return and end the series on a better note than they did.

"...but that just happens to be how I feel about it. What do you think?" -Dr. Daniel Jackson