Hayo,
Would you purchase a word processor or text editor that did not have an undo feature? No, absolutely not. So why should we expect anything less from PM?
I was able to recover from my mistake because I had a backup copy. We all know we should regularly backup our data, but for many reasons we don't or we don't do it frequently enough. In this case, I was lucky and I had a recent backup.
I certainly understand that PM does not have an undo feature. As a result, before I apply an IPTC edit to more than a couple of images, I check the edit on a single file. I did so in this case, and it was fine. What I did wrong is copy a key piece of data unique to that particular image to all the rest (thus wiping out that field -- the field I had spent hours keying in).
If the recommendation is to always backup your data before applying a large edit, then I would argue that this slows down one's workflow significantly and that this is contrary to what PM is designed to be (i.e. fast).
I also think that having such a feature would be a strong marketing point for PM and make it more successful.
From a technical standpoint, I don't see it as difficult to implement a single level (last change) undo. There is just not that much data in each IPTC record, so saving thousands of images worth of data is not that significant.
Perhaps an alternative solution would be to provide a backup IPTC command where the user could backup the data first and then apply the IPTC edits. If a disaster occurs, then one could recover the old IPTC data.
Deven
