If the user wants to put text on a hairpin (as like with regular lines), the options are to have begin + end text. Problem here is that the text "removes" portion of the crescendo. This makes sense for the most part with things like dynamic markings so that the hairpin conforms within dynamic markings, or texts of that same style.
If the user wants for instance to put text [above] the crescendo as with the above/below text options, the result will not be appropriate. The length of the text, even if "above" or "below" is selected for [end/begin text], the text will remove portion of the hairpin, and it's not recoverable! Meaning, CTRL+Left/Right won't expand it, so there'll be a gap of space between the first anchored note and the last (either beginning or ending depending on if begin/end text or both).
So, if the user wants a full hairpin with an additional "text" line above/below and centered on it, this seems not doable and will require another staff-text or the like. This seems to be a bug or at least a lack of a feature mixed in with pseudo-bug like behavior in attempting to achieve it with current options. This could be useful for instance if the user wants to use things like "Accelerate" or something of the sort mixed with a crescendo. It'd be nice to have it be connected with the hairpin, centered, not removing any space from the hairpin, with the addition of being able to save the customization to a palette for later use. As it stands now, saving isn't doable because the offsetting (center-text doesn't act as it would be desired for such a task) in the X co-ordinate isn't saved when applied to a palette.
Maybe a little screenshot will help also:
This should be upgraded.
P.S. The comment about not being able to extend via Ctrl+Arrows was with the implied assumption that there was a dynamic marking after the hair-pin. The dynamic mark will block the hairpin from extension. Otherwise, the user can do so, of course.