One alternative way to find tags with no tag wiki is to visit the NEW tab on the tags page.
This will give you the latest added tags and those often doesn't come yet with a wiki or excerpt.
As you see how many questions already have the tag you can judge how valuable an excerpt/wiki would be. As a bonus you spot misspelled tags (retag those questions so the misspelled tag gets removed at 03:00 UTC) or tags that either should be synonyms of existing tags or simply be replaced by a better tag.