I guess this wouldn't be trivial to enable, but I'll post it nevertheless...
So, the task scripts should support simple program flow concepts, like conditional branches and loops. This should possibly not be too emphasized, to keep things simple for non-programmers, but it'd be nice to have anyway. Loops should be possible to iterate a given number of times, or over a list of files.
Also, supporting simple named variables would be nice. Nothing fancy, just strings, maybe with a few numerical operations, which would work if the variable has a valid numeric string value. Those could be assigned static values, or the contents of the clipboard, or the current selection.
*Maybe* file lists obtained e.g. from a file open panel. Even better, if lists would just be a string with items separated by some special character, then it could function as a list for files, windows or other string-like things. Then loops could be had to iterate over the items in such a list. A few macro steps could be used to get some interesting things into such lists, like various kinds of windows (existing, visible, minimized etc.), or a file list from a file requestor, anything.
I know this is quite advanced, and I don't really expect it to be realized, but it'd be nice anyway (: