I got interested in a TV show a few years back in the USA called Surface. They have most of the episodes on Hulu now, and I've been rewatching it. Unfortunately it was only on for one season. The show had quite a few viewers (nearly 9 million), so I couldn't understand why they pulled such a good sci-fi show from the air. After asking around, I found that it was pulled for financial reasons. The show used a lot of CGI, and CGI is expensive, so even though they had as many viewers as many other shows that are still on the air, they really needed a vast viewership to stay on the air if they were going to pay for the CGI.
Moral of story, if you're an aspiring filmmaker, CGI can be the kiss of death unless you have a blockbuster on your hands. Approach with caution. There's a lot to be said for traditional storytelling and allowing viewers to use their imaginations in place of expensive CGI.
I hear Fringe is being moved to Fridays next year... usually the place TV shows go to die. Apparently its CGI is also a factor.