I think the cost of producing SGU was pretty high, with the relatively large cast and FX, and exceeded the revenue from the low ratings it got. The MGM bankruptcy probably didn't help matters. I imagine that Caprica went through something of the same thing.
Still, I liked SGU a lot, though I never watched Caprica. I imagine a lot of Stargate fans wanted Stargate: The Next Next Generation, put that formula was getting rather stale and they needed to try something different. It's unfortunate that they failed.
Terriers getting such low ratings is a shame.