I can actually see some advantages to not transfering over updates to lists as sometimes these need to be update in live, even although dev work is going on.
Not updating roles could be problematic though, as these do get updated quite a bit, especially if there are process changes, then there are usually role permission changes that need doing at the same time.
I agree that it would be better if the items were compared and then there was a prompt asking which of the items to update and which to leave unmodified.
As you say Peter, sometimes you do and sometimes you don't, so making it optional would be much better IMHO for each difference found; we're used to this in Design Transfer for example.
Also as consultants we have a proven procedure for first moving design from DEV to UAT and then post-UAT to LIVE; if there are any issues then they can be addressed close to the LIVE sync via testing a current copy of LIVE again first near to the point of the actual LIVE work. At least then we know we can retrace our footsteps with the actual LIVE sync and get the system back online quickly. Now it seems we have post-sync design work to document and re-do again.
Also I think it was pretty clear message to users of LIVE before, don't touch anything in LIVE during the "Design Freeze"! Now though they can do limited changes so going to "muddy the waters" somewhat IMHO on how to communicate and police.