After putting together a post, before actually posting it, the Preview feature allows you to see the post as it will actually appear .
This has a number of advantages :-
1. Spotting typos
2. Checking links (i.e. you can click on them in the Preview screen)
3. Checking whether the italics feature works
4. Finding out if auto-censor has redacted anything
5. Last but not least giving you a chance to reflect (as recommended by Ed) before deciding whether it contravenes site rules etc.
If you are happy then "send", if not then edit or delete. I have occasionally (on Fora with this feature) decided to bin rather than publish. It stops you rushing headlong into trouble without having thought it through.
So folks, join the clamour (well, just me at present) for this feature now.
//I firmly believe this feature would lessen nasty posts.//
I doubt it very much, for some it would be a great opportunity to add a bit more venom or nastiness in.
The other problem is that some of us dont have much time. Quite often I will post up and then have to go. If I am spending abit of time on AB I do as NAomi does. I have lost too many posts over the years after spending time typing them in only for AB to collapse. (Doesnt seem to happen these days though thinking about it.
Having said that, so long as it could be turned off then it could be useful.
So long as it's optional I think it's a great idea. I would certainly use it for longish posts or posts containing links but probably opt-out for quickies.