Just wondering: when did LDC become in charge of determining what Wikipedia's syntax should be?
WRT to the double/single bracket issue: We're suffering from a legacy problem, since the double-bracket syntax was originally uncommon (as opposed to CamelCase), it was okay that it was more tedious than single-bracket.
The best thing from a usability standpoint to do would be to switch from double brackets to single brackets.
An advantage of using double breackets only is that we'll then be able to use single brackets as regular punctuation, which would be especially handy in math articles, among others.
The answer to your first question is easy--you know where the code is. Like everything else here in Wiki land, the "authority" falls on the ones willing to do the work.