There are two reasons why I am using forceId, but both of them are probably because I am not doing something correctly.
1) When I use an addMessage(id, ...) I have to specify the id of the control for the message is intended. It seems (maybe I am wrong) that if I don't use forceId, the id used in JSF isn't the same as that referred to in the addMessage(). 2) I am using ajax4jsf and I was getting lots of duplicate id's. When I used forceId, those errors disappeared. Maybe there are better ways to avoid these issues, but forceId worked for me.
