Well a generative patch is basically a set-up that plays itself or needs very little human interaction. So perhaps when people state they're looking for a "generative" set-up. They aren't really meaning to go that far and just want something that creates evolving sounds.
In a generative environment, you'll see loads of sequencers, switches, LFOs, VCAs, and clocking sources. You'll find sample & hold circuits, lots of effects, etc. I think there's a false believe that generative, ambient, or "drone" set-ups are simple.
I don't think anyone can tell you buy module X or modules X,Y, and Z to do 'generative' stuff. Everyone will use a module differently or use a different set of modules to get the results they desire.
I would recommend practicing your patching. Rather than worrying about the sound so much, worry about creating relationships between the modules that can change dramatically based simple differences in one sequence or the timing of a reset trigger, etc.