Of course, if Larian have left the capability for the game to be modded then it's possible that mods will one day be available for it if they release a toolset, or if one can be created for it.
Modding is, generally, seen as a good thing with PC games so I don't think RPG and RTS developers are against it as such, but if you take Dragon Age as an example then the existence of a toolset might not necessarily be a good thing. The DA toolset is utterly terrible compared to previous toolset releases for games that use BioWare engines, and it's had a grand total of 0 support since release. At least you can understand it with, say, Unreal Engine 3 as it's a commercial engine with a lot of limitations attached to it, plus I understand it's not the easiest thing to mod (Can't think of a commercial UE3 game with a toolset, personally. Well, GoW PC has a "game editor" but I've no idea what it does).
As Larian are a smaller developer, they might not be able to promise the resources needed for creating a user friendly toolset (They're often, if not always, released for free to the community - Don't forget that, and as such development/support is at the developer/publisher's expense) and for providing support for it and its users. They'd also, potentially, have to provide support to those who install mods and somehow "break" their copy of the game (Come on, we've all done it).
That said, I don't really see what could be done with Divinity 2 in the way of modding. Beyond gameplay tweaks and item creation/adjustment, it seems pretty limited. Bethesda's titles, the NWN games, Civilization and Total War - They were built with modding in mind, but something about Divinity 2 tells me it wasn't, and perhaps for that reason alone Larian won't support it.
