Feature summary:

Currently schema includes timestamp of the current (dumped) revision. But it would be useful to also have date_created timestamp to tell how old the article itself is.

Use case(s):

It is useful to know how old the article is, especially if you are also trying to infer when some things happened and were recorded in the Wikipedia for the first time.

Benefits:

I think it is one of those simple stats which simply make it easier to understand better how the article came about to be.