Yeah, Maul wasn't the Maul villain. Hell until TCW he was barely a character at all.
I do get the point though, after bringing him back from the dead it's a little off not to show his "actual" ultimate fate. But, as others have said it's not a huge deal in the grand scheme of things. While I'd be interested to see where they were going with him, I'm not exactly champing at the bit to know.
I'm *much* more interested to know what happened with Ashoka and Asajj, but even so, I'd rather the new show have time to get it's space legs and break some new ground before it starts getting into that sort of thing.