I do think this is important. However, . . .
Having had one tag wiki excerpt suggestion rejected already, I'll remind everyone about the rejection reason:
Simply defining what a [tag] is rarely helps those using it unless the tag's name itself is ambiguous. Excerpts should describe why and when a tag should be used. See the help center for more guidance.
I've started this, with a few tags, including license. However, while doing a complete tag wiki is important, we should get started primarily with tag wiki excerpt. This is what people see when tagging their question, as well as on the tags page.