"before" and "after", why not on all types of fields ?

The title says it all, how come the ‘before’ and ‘after’ options are only available for ‘textfield’, ‘select’ and ‘file’ fields ?

This is very unfortunate, those options are very useful to add some texual information on the field, for example I use them to give the user precisions on how to fill out a field.

Or is there a way to do that otherwise ?