I'd love regular expression support.
From the developer's point of view, I can appreciate it's not a friendly or easy to understand syntax. But I'd still love it. It'd be great for more accurately matching filenames to move to folders etc., but even better if it was supported in renaming/moving.
For the matching of conditions I would imagine it could fit in more easily, perhaps in the drop down "starts with" there could be a "matches expression" or something... I dunno.
Just throwing the idea out there as I didn't see it anywhere else... I guess in the meantime I can look at writing a shell script for the renaming side. I've not started to play with that yet, though.