I hear everyone's input here, but I think that you're looking at it from the wrong perspective. IDPS is part of the paid licensing package from Untangle. As such, the end users should be demanding from Untangle to step up their game and provide a (somewhat) functioning out-of-the box/moderate configuration-needed IDPS. We shouldn't be making excuses for Untangle why they can't provide a basic rule set because it would add to their support costs, the same way we shouldn't make excuses for SonicWall, FireEye, and Palo Alto Networks. If their customers demand it, then the company should provide it or lose those customers to other companies who do provide it.
I don't think that this is such an outlandish idea.