User blog comment:DaNASCAT/FANDOM Increasing HTTPS Support To Improve Security/@comment-5973717-20171027161726/@comment-27345308-20171027163254

OneTwoThreeFall's reply here sums it up pretty well. Wildcards can only be used on the single left-most level. If the domains were structured like  that would be possible and it could be affordable for Wikia to have their certificate cover 300-400 subdomains for each of the language codes they support (though they would probably only cover 11 for languages they have Staff members in). With the current URL structure, however, they would have to cover each non-English community, which would probably mean reissuing their HTTPS certificate every time somebody creates a non-English wiki. Not to mention HTTPS certificates cost money.