Seth Green spoke to Jenelle Riley at Backstage.com on April 11th 2006 about why he left Buffy. He said:
I’m a big fan of the show and enormous fan of Joss Whedon–I love that man. It was a hard thing to walk away. But when I signed on to that show, it was as a recurring character. That first season I was on, they gave me a bunch of great stuff to do, but there was a lot of promise about what the character was going to become. Because they wanted me to be a series regular, they had to write me into every episode. My whole second season, the plot line they wanted to do had so little to do with me that they were forcing me into every episode like a square peg in a round hole. And it left me feeling like I wasn’t getting the creative satisfaction that I was being offered elsewhere. I would essentially work 12 to 18 hours a day. There were forced calls all over the place, which means you don’t get your 12-hour turnaround, which essentially means you don’t get to sleep. I did Idle Hands the same time I did Buffy, and I would go in about 6 o’clock at night and work until 5 in the morning and then have to be on set at 6 a.m. on Buffy and sit through hours of makeup and work 12 hours, then go back to work on Idle Hands. I had a couple of 48-hour days and I thought, “This is insane.” I literally couldn’t do anything else in my life, like make a dentist appointment, see a friend of mine, have a birthday.
It just became a claustrophobic type of schedule. And that’s all fine and well if you’re getting some type of creative satisfaction. Joss and I talked about it at the end of my second season, and he said he had some great ideas for me for the next season, and I told him I would be happy to do it in a recurring capacity but being a series regular, it just didn’t work. All the writers were trying to fit me in, and I’m winding up spending five days a week, 12 to 14 hours a day, so I can sit in a crowded room of a multicharacter scene and say, “I think Buffy’s right.”
We left it on pretty good terms; I came back and did two episodes after I left. It just, creatively for me and I think for the show, didn’t make any sense for me to be there. I know a lot of people were upset, and I so appreciate they connected with me and the story line.
I’ll confess something to you: At the time I left Buffy, I was the least-paid person on the show. I had been in far-more-successful stuff and found that unbalanced, as well. I understand it was an upstart show on a fledgling network and they just did not have the money to pay. But it did not make sense to me to be killing myself with no social or personal life, missing opportunities in other areas, and physically depleted because I was working so hard.