Interesting suggestion. However, I think to suggest that the Forgotten are "quick to forgive" is taking an extremely human-centric view on things. Humans pushed them into the desert in the first place, and in a sense, they were here long before humans did. I think it's also reasonable to think that the events you see in Prophecies are exceptional, rather than the norm - your PC was a part of the Flameseeker Prophecies, and Glint was guiding events along, too, so I felt the fact that Glint took an interest in you was the primary reason in why they helped you out. Below is a portion of the skill point quest from one of the Forgotten NPCs you encounter.
Know then that we Forgotten were the first race to rule Tyria. During our reign, the world was at peace until your people came, until the humans came. We could not compete with the savage humans and were slowly driven into this desert where we met our future master, the great crystal dragon Glint. It is she who you must seek if you wish to Ascend.
I also wouldn't say that their civilization has survived. Their outposts and positions in the Mists are being overran thanks to Dhuum. Mallyx the Unyielding is making huge dents in their numbers, and I don't think (just my interpretation) that they're doing all that well. NPC dialogue everywhere (especially those from quests in the Realm of Torment) suggest that they're also a race in decline, and that whatever their interaction may be with Tyria, their time is also ending. The last major deed we know of is that the Forgotten aided Kormir in cleansing Abbadon's realm. Though whether that's due to a willingness to help humans or a willingness to see the end of their duties - which is also mentioned by those very same keepers, I think, is an interesting debate best saved for another time.
Unlike the Mursaat or the Seers, however, I think you make a great point in the Forgotten are probably one of the most likely to help out humans in the event of GW2. They've always been staunch supporters of the Five, after all, and they do see the containment of Abbadon's forces with a zeal that borderlines insanity - Yithils is a good example where he basically tells your PC that he'll fulfill his "sacred" duty so long as one of his people is still remaining alive.
Edited by Steadfast Gao Shun, 01 November 2012 - 12:05 AM.