We discuss the sense or nonsense of the preview feature over there in a Github-issue (#638). Please read the arguments in the issue, I don't want to begin with a repetition here.
The feature makes it necessary to adapt many changes of the handling of entry content, possibly with special cases for only this one feature. Currently it's the handling of the optional JS-library MathJax, which might be necessary for technical or scientific forums only. The library formats mathematical formulas from a LaTeX source in a forum entry. Next time it could be something completely, something, that would affect everyone.
So most of the forum operators will never need the currently affected library. On the other hand, cases like this makes it necessary to handle the view with special treatment (what we call an "Extrawurst" in German), completely independent from the number of affected users. It might be one forum or all forums, that run with MLF.
The result of the discussion so far is, that we (Micha, Alfie and me) doesn't really use this feature. So we want to ask you, if you as forum operators and your audience use this feature in a serious manner (not only once every when and then). If not, we tend to remove it.
Trenne niemals Müll, denn er hat nur eine Silbe!