There may be value in temporarily doing it to allow new users to get familiar with the appI would say do it the first time or 4 and then have a never do this again option. That way when they are still getting familiar with it they can undo.
High risk publications may also benifit from a preview. Ie changing your relationship status or your place of employment you may want to preview it first. Imagine if you changed your place of employment and had autocorrect spell the name wrong, that preview feedback loop is a second chance at checking your work catching an error and posting something of higher quality.
Why preview text only posts?
To show the context of where that text will be going and give a user a chance to undo as they are getting familiar with the system. IE you intend to send someone a message "I cant stand my boss karen.." but you just downloaded the mobile app and fat fingered the status update form instead of what was the message button. Or you posted it on her public wall vs in a private message.
Its similiar to the cc all mistake. You cant prevent it 100% but for new users a preview of where that text is going "may" be useful. I dont have any concrete research to say one way or another.
For posts the user does multiple times i wouldnt do it. Ie if they are very familiar with the feature IE their 10th-1000th tweet , theres no need to preview in my opinion.
You want to make it friendly and easy to prevent mistakes for a novice while not slowing down an expert