Something I want is a sandboxed place to run USER scripts in game. I trust the game's creators to not hack my machine with their DSL (else I wouldn't be running their game). I don't trust random drive by game mod to the same level. I'd love not to have to trust user additions, but currently I do have to trust them or go without.

I run a few games that takes C# plugins. The games have a big warning that they aren't doing anything to prevent my machine getting hacked, personal files uploaded to random servers, etc....