People are trying to put something in a community ("investment") and get something out ("return") without any sense of the complexity and richness in between. Early psychologists felt the same way about the human mind - 'avoid this subjective experience nonsense'! Stimulus, response.
As a result, empty metrics are passing for ROI. Page views, photos uploaded, unique visitors are used as proxies for dollar amounts. People are confusing value and return. Beyond the fact that ROI needs to reflect money gained/lost vs. money invested, there's social value not being captured in a very social medium.
Now this doesn't mean we all need to chase the illusory grail of engagement... lest we prove it a sound construct. My point is, the innards should not be ignored, even if they chalk up to "soft," intangible value that doesn't enter your ROI calculation. Often, there are emergent outcomes.
Philosopher/Scientist Bruno Latour discussed why it's a problem to blackbox:
"When a machine runs efficiently, when a matter of fact is settled, one need focus only on its inputs and outputs and not on its internal complexity. Thus, paradoxically, the more science and technology succeed, the more opaque and obscure they become."Our intuitive sense that a community is running smoothly could paradoxically lead us to ignore what makes it tick. Let's not make this mistake. Web 2.0, by any name, stands for the opposite of black box thinking. It's about exposing and creating value from the inner components; glass box thinking.
Lastly, let's not misunderstand this argument: Again, the metrics that tap into the depth of members' immersion in a community are not ROI per se. I recommend measuring something social; use that to predict your business goal (e.g. Retention, Satisfaction). Then, calculate your ROI ratio.