I would have liked to know what led to my ban without having to come here. I don't mind the ban, but I also like to know what I did wrong and how I can improve myself, especially since the SE sites are about helping each other.
At the same time, advice and recommendations about what to improve with the "You've failed too many..." message wouldn't hurt anyone.
Something like:
You've fallen into the honeypot. Here are some tips to help you make better reviews:
- Take the time to carefully read the answer/question you're reviewing.
- In doubt, skip the review, someone else will review it.
- (add more)
The same would be possible for (manual) moderator bans, where they could select a "canned" tips message and/or add a comment of their own if they feel it is needed.