Applying the format string to the form view just doesn't make sense / isn't possible. It's intended for display purposes. Take currency, for example ... you don't want the currency symbol inside the input ... or distance, you don't want the 'miles' or 'km' inside the input field.
If you do that, such that the element's form input is "5 kilometers" ... then you take that value and apply a format to it for display, you get "5 kilometers kilometers".
Best approach (IMHO) if you want to make it clear that an input is (say) distance in kilometers is to use an HTML 5 placeholder ("distance in kilometers"), and apply the "%s kilometers" format string to it for display in list and details view.
The only other potential solution is to use an input mask, but again, that raises all kinds of potential gotchas.
I did consider, a while back, adding a "suffix label" to elements, so you could add text after the input field, but that's a lot of work tweaking a lot of element layouts.
-- hugh