Personally I think it would depend whether I were selling a lot of my work otherwise. I'm not, so for me it would be interesting to be involved in a project like that and see my work in print. Yes the publishers are going to be making money out of it, but it wouldn't be costing me anything. Look at the positives, your work is obviously good or they wouldn't be asking.
Which is a long way of saying, are you going to get pleasure/a buzz out of doing it? If the answer is yes then why not!