Hooks API is available in 4.4dev and used to allow extension of course edit_form by plugins.

Questions are another moodle element where custom extension is usually needed. For instance, a University could need to label questions by Department, linked to a custom department table (not just tags). Or adding other fieds to questions of any type.

In fact this issue is related to  MDL-80964,  where modifications are restricted to qbank_ type plugins. With hooks API available, it seems more generic and prefereable to get that functionality in the hook way, and then available for any plugin type (for instance, local ones)

The proposal includes a patch file against moodle head

The quiztimer.zip file is a test plugin (disposable) showing the use of the hooks to add two fields to que question_edit_form