As most of the data sources could do -directly or indirectly by a mf- an association data source does not have the option to manipulate (the default) sorting when retrieving items. Of course you can make your own sorting or filtering logic.
By giving the default sorting options, there would be no need (in some cases ) to build exta sorting mf’s, will save the developer some time and also important: keep the code with less logic and more clean.
Agree! (this should already been there in version 1)
Really good idea.