Last modified: 2014-02-12 23:53:01 UTC
The language attribute is readily available from the langlinks table so can easily be added and should be added for accessibility.
For an example of how this makes a difference, turn on 'VoiceOver' mode on an iPhone or iPod Touch and try having it read out some of the language names -- the ones in languages it recognizes go a lot smoother when the lang attributes are there. :)
https://gerrit.wikimedia.org/r/30959