Some time in the last few weeks the crash-reporter stopped remembering the email address field: I have to type it in every time now. I have seen this behavior on both Mac and Windows; Andrew has seen it too.
note that it's only a minor annoyance to me personally to have to type it in (although annoying enough that sometimes I don't, or remember just after I've pressed the Submit button). I'm more worried that we'll have fewer email addresses to use next time we have to track down a mysterious crash since I've made use of that data.
The crashreporter code hasn't changed in a long time, I wonder what's going on here. Can you try an older build and see if it reproduces there?
I noticed this problem a month or so ago maybe and I just assumed it was some privacy adjustment. On the other hand, it did remember my email address at least once recently.