Tag badges currently only are funded towards by votes on answers. However, on some sites, this is not appropriate.
For example, on PPCG, a great deal of work and knowledge over a tag is in writing questions; we have a user (@HelkaHomba) who has written literally hundreds of questions in multiple tags and yet does not even have a single bronze tag-specific badge. However, as @AlexA. pointed out in the first link provided:
I had a brief chat with a dev and apparently this can't be set on a per-site basis; the change would have to apply network-wide. He did recommend leaving this up and seeing what kind of support it gets though.
Since it is appropriate on some sites, but not others, making this set-able site-specifically (and then, of course, changing it site-per-site) would be best.
EDIT: As @MartinBüttner pointed out, it might be better to award tag badges for questions separately from tag badges for answers. Please consider this as another possible feature-request candidate.