With SiteCataylst 15 migration we noticed that error pages report disappeared. The only solution to this seems to be an additional prop = not handy at all.
We would vote to re-introduce error pages report.
I've actually been working on this problem as well. Decided a nice workaround would be to use dynamic variables in the pageName so we can not only see what URL's are being accessed, but what paths users are taking to get them there. Here's what I'm setting for pageName on my 404 error pages:
s.pageName='D="404 ERROR: "+g';
This way I can easily filter my Pages report to 404 ERROR and also get a complete list of URL's.
Wasting a prop on this doesn't really seem worthwhile to me either.
We had to add it back manually. What a pain. Why do they keep taking features away!!!