Per http://www.mediawiki.org/wiki/WfMessage#Comparison_with_the_deprecated_wfMsg.2A_functions
At some point, wfMsg(*) should get replaced with wfMessage(*)->text(), either by regex and script or by diligent editing of text files. I'd call this "easy", but I'd also call it "a really tedious task".
In any case, it should probably happen. I'd accept review of this theory from l10n/i18n people.
Version: master
Severity: minor