The change for ignoring null input values has gone live:
There is now a $esc.jsonDecode() method to allow you to unescape a json escaped string into json without having to do a bunch of string search and replacements.
$esc.jsonEncode() was added to have the same sort of name as $esc.jsonDecode(). This velocity macro is identical to the existing $esc.jsonString(), with no plans to remove the old macro.