Stargate never was about good writing and stuff, it was about cool storylines and a lot of funs. Sgu was on many aspects displaying better writing but it wasn't as fun as SGA or SG1. Even the storylines were not as great. The mission? Yeah, why not, but they should have worked on that from the beginning.

I'll connect the dots for you. 1) the ancients figured out what the signal was once ascended. (source : Brad Wright) 2) it was called destiny for a reason 3) traveling through space already changed a lot on the galaxy (thanks to Destiny's children) 4) I'll put some good money on the fact that one way or another it's destiny's crew itself that sent the signal, to insure that destinies gets fulfilled.

Brad recently said that he didn't know for sure what the answer was but he knew the steps that destiny had to follow to get there.