Originally Posted by azarhal 
Modders don't need mod tools. There were none for KoTOR or the Infinity Engine games and that didn't stop people from adding content. Modders only need easy access to the game content, which is what Obsidian promised us here.
Actually, I think not having mod tools is a good thing. Too much commitment required, which mean only the dedicated modders will bother with it.
Also, if you feel like it, any Unity game can be "modded" by Unity (except that the Pro Version isn't free).
The games with officially supported mod tools have so many more mods, and much better mods.