They screwed the pooch by going to another galaxy where there were apparently only two different races, forming about three groups, and none of them were really worth talking to. An entire galaxy, with basically nothing in it. The only emptier place was the Ori galaxy in SG-1.
When SG-1 was in its early seasons, the team was running across all kinds of things, from the fish man looking for his lost wife, the little crystals containing sentient consciousness, the funny little mushroom trees with sentience and funny little elf helpers, the torment of Tantalos planet, the planet where everyone was in the matrix, the planet with the Dom Deluise entity, many planets with weapons that could stop the Goa'uld, both destroyed and still functioning, the planet with the Wormhole Extreme! creator, the Nox, and of course a variety of primitive or Goa'uld worlds. And we were just starting to explore. As time went on it came down to Asgard, Replicator, Goa'uld, and finally just Ori and a few Jaffa worlds. SGA reduced that down, to seem like a galaxy with a dozen planets and not much variety, instead of presenting a new galaxy with even more wonders. SGU was like flying through a post-apocalyptic void in a prison bus, looking for derelict gas stations.