I think people who are saying they should take the pay cut are missing the point here. These are the guys who make the show, and Fox itself has been making billions of dollars off of it, with no end in sight as the show is quite iconic. With the amount of money Fox is making, why should these guys be the ones to take the pay cuts? I very much doubt the show has stopped making enough money to justify those salaries, it's probably producers wanting to maximize profits by cutting costs. If the show was losing money in any way, shape, or form, then the offer of trading a pay cut for a percentage of the profits would be fairly attractive.
To be honest I think this stinks, I think there is a growing amount of disrespect in the TV industry for their talent since the entire "Charlie Sheen explosion", and even he had some pretty solid points about the amount of money they were making off of him, he was just a jerk about it. I think a lot of people see what happened with Charlie, and figure they can now leverage a lot of their highly paid talent, in hopes they see the example made of him and say "well, we can do this to anyone".
There is another aspect of this as well, and that's simply that the guys doing "The Simpsons" have been biting the hand that feeds them, which is never a good idea. Some of you might remember discussions revolving around an episode that featured a Fox news helicopter that had "Not racist, but #1 with racists" on the side or something like that, and apparently that wasn't their first move like that even if it was one of the more overt ones. The lack of any kind of immediate backlash right then and there doesn't mean that the guys in charge don't bide their time. The Simpsons has some fluctuations in performance, and now people that might have sucked it up to begin with are using it to justify cutting the pay of a group of people that doubtlessly contributed to slotting them off.
My basic point with all of this is that I think the situation is far less straightforward, and that there is a lot of thought behind it. Right now the response that these guys should take a pay cut is EXACTLY what Fox is banking on since it puts them in a position where it will seem fairly sympathetic if they DO decide to cut the show. That's one of the reasons
why a point is being made about these guys getting 8 million dollars a year, the numbers are usually kept vague unless there is a reason to release them, and the reason here is they want people to go "WTF, 8 million a year for voicing cartoon characters?". That's a lot until you consider these guys are big name actors (as 23 years of success attests), most of them probably could have gone on to many othr projects but instead remained committed to Fox and keeping this franchise running for them.
Fox are being a group of jerks, but at the same time I think the voice actors probably brought this upon themselves. A bit of political satire is one thing, but when you insult your bosses and their platform(s) directly, and rely on being too big for them to do anything... well that kind of thing tends to backlash in the long run. As I said, I think there is some payback here, the whole "helicopter" thing just being one of the more infamous examples, there have been others.