Should `fill-paragraph' respect formatting?

[Tor Kringeland]

I sent the following to an `org-mode' mailing list:

> Applying `org-fill-paragraph' to /e.g./
> 
>   /Some text./  Some more text.
> 
> when `sentence-end-double-space' is t removes the double space to a
> single space.  The same happens with other formatting like *bold* and
> _underline_.  In other instances it is more context aware.  /E.g./
> applying it to
> 
>   (Some text.)  Some more text.
> 
> does nothing, which is correct.

`org-mode' binds it's own variant of `fill-paragraph', but should the
default `fill-paragraph' respect formatting like this also?  /E.g./ when
writing text outside `org-mode' (or something similar like
`markdown-mode' for that matter), like in an e-mail, it's not uncommon
to use formatting like _this._  Or is it better to leave this to individual
major modes?