Re: Why the random episiodes?
Actually season seven was meant to be the end of the series, and Atlantis was meant to carry on from there set in the Milky Way with the Replicators as the main villains. It was only when SG-1 was renewed again that they invented the Wraith and Pegasus Galaxy for Atlantis and went the wrap-up route for SG-1. I don't think people meant the writers gave up on it, more the actors. They knew their positions were safe, and RDA in particular started really phoning it in from season eight onwards.
Seasons six, seven and eight were meant to final seasons of the show, I believe there was even a series ending wrap party after season six ended. And the actors continued to write and direct eps. in those final seasons so I really don't think they gave up either.
The greatest science fiction series of all time is
Doctor Who! And I'll take you all on, one-by-one
or all in a bunch to back it up!"
--- Harlan Ellison, from his introduction
to the PINNACLE series of Doctor Who books