Syfy cancelled Stargate SG-1 because the network was pivoting to putting more effort into their other shows like Eureka which had a more general appeal. The writers snuck this cryptically meta exchange into S10E18 “Family Ties” poking at the network for how they felt the series was being mistreated.
In my opinion, it was a mistake to make seasons 9 and 10 of Stargate SG-1 instead of their original plan of making it a spinoff called Stargate Command. If they would have started fresh as (technically) a new series, I think it would have been overall better for the long term health of the franchise.
I mean, depends on the format of Command. I liked the format of SG-1. And Atlantis. Universe doesn’t exist to me lol.
I watched Stargate Universe again recently, and it did not get any better. That show did try some neat things and had some good things going for it, but at the end if the day, the main focus of basically every episode was interpersonal conflict drama, and that just does not interest me.