Eeeer... to get back to the subject...
I am interested in the rights of 'lurkers' vs 'posters debate - it's a good point aitch. I could probably be described as a lurker - have been a member for 3ish years, log on most days, but post very infrequently. I love mumsnet - it makes me laugh, sometimes makes me cry, it widens my horizons, and it puts me in touch with intelligent women when I think I will go stir crazy if I have to play for the fiftieth time that day.
I also use mumsnet as a valuable resource tool - it's often the first place I come when I have problems with my dds, usually before google! And I frequently read threads that are older than a year. But they tend to be threads on health issues, breastfeeding, children's behaviour - never relationships/aibu for example. I have found it incredibly useful, and would be sad if it disappeared through removing the archive.
But... if I was a poster that had posted my views/personal details on threads then I would also want to be able to remove/edit them if i saw fit - especially as the site constantly evolves and changes. Why should I, as a lurker, have more rights over content than the person who actually wrote it?! What might feel ok to post today, may not tomorrow either due to changes in personal circs or in the MN environment. I think to prevent this (or as in MN case, ask posters to 'ask permission') is backward and makes me feel very uncomfortable. The MN archives must be enormous (I rarely search and get less than 500 posts back in response!), so the argument that you could 'dilute' the boards doesn't wash with me. I cannot see the reason why MN couldn't introduce an 'edit' function that allows the reader to see that the post has indeed been edited. Many other forums do this without detriment imho.
I also think that there is a case to remove the archives on certain (more sensitive?) topics like relationships for example.
FWIW (while i'm doing one of my very rare posts!) I don't like the DM development. And while it may be within the 'rules' of MN, I feel that the spirit of this community has somehow been violated. And this makes me sad.
I'll go back to my lurking now!