What's this WeiDU thingy? The only thing I've found out on it is that it's easier to script in..

WeiDU started as simple infinity engine dialog utility for making your own dialogs. Today it's ultimate mod installation util. It doesn't just make dialog modding easier, but allows you to change/add anything you want in the game.

And is that good for the gamer? Except for more and better mods in the future.

For the gamer it has a specific benefit: you may install/uninstall WeiDU mods without fear that something will go wrong and force you to reinstall the whole game from scratch.

Right. While we WeiDU mod developers are not perfect--and it is still possible to make buggy or destructive mods using WeiDU--it gives players a lot more flexibility than ever before. It also makes certain development tasks MUCH easier than they ever were before, which indirectly means more mods faster.