Well they could offer payments in a fixed dollar value. Maybe that would be better for everyone? At least people wont be worried about losing money then. Is there any negative effects to doing it this way?
It would be very hard for bitmixer.io to do, as everyone gets paid at a different time, so the bot probably would have to calculate the bitcoin price exchange constantly, and the bot would have to convert that amount into bitcoin in real time and send it. It would be quite hard to do.
For all the people complaining, if you think the rates are too low, just join a different signature campaign. Simple.
Also, I see some people complaining about the rates when they aren't even in this campaign. What's the point of that?
I don't think it would be that hard to do, especially not for a bot. Sure, slightly more work than just paying a flat 0.0007 but maybe the rates should be reevaluated every once in a while if the price falls dramatically or continuously but like I said above most campaigns don't seem to have bothered changing their rates with price rises or declines.