It is great. It is better than using Greasemonkey and also in mobiles and all, it will help very much.
If you really think rogue scripts are really an issue the setting could be put in an hidden place, only js files from github/pastebin/etc could be used, js files must be pre-approved, etc.
Yeah! Something like that should be included. Do it need a separate staffs(new) who are trustworthy and have skill in languages atleast Java? It would be great than Mod/Admin approval. OR they can make 2 approvals, after staffs(new) approve the script, they can submit an approval ticket(or something like that) to Admins and then Admin can approve the script. I think the 2nd option would be more secure but only if Admins are less busy.
~~MZ~~