This question goes very deep. If you pursue it then at some point you end up asking very deep questions about value, ethics and meaning.

Unless you want to set a few boundaries to keep the debate about more prosaic matters then be prepared for a long night.

The question is actually based on the false premise that value can be objectively measured/quantified.

In fact, value is purely subjective. In other words, the value of 'Wikipedia consumption' is only what each individual places on it.

For example, someone may find Wikipedia valuable in pursuing his quest for greater knowledge, whereas someone else is completely uninterested in 'consuming' it (and doesn't see Wikipedia as valuable).

In a nutshell, the value of X is its subjectively perceived utility as a means towards an end.

See http://mises.org for more.

It adds to human capital, which we can't quantify as of now.

I'm not sure if we'll ever find a good proxy for how much information is worth as it is an extremely heterogeneous, intangible input that goes through a complex, unstructured, and not-fully-understood process (the human brain) in order to create value in the world that we can measure using money as a proxy - a company's revenue, for instance.