In the policy for new languages, there is a requirements for the localisation of the "most used" MediaWiki messages. These messages have been stable for over a year. This ensured that there was a stable target to shoot at.
Recently Siebrand did some profiling on the MediaWiki messages, and the "most used" messages were no longer the most used message. Consequently there are new "most used" messages and the statistics for the most used messages took a nose dive.
I can imagine that people may be upset about this. But the reality is, we require the localisation of the "most used" messages because they are the most used messages. Profiling which messages is a lot of work that is done only occasionally. I am grateful that the composition of the most used messages has changed. If anything I would welcome regular changes to the "most used" messages because it demonstrates vividly that localisation is shooting at moving targets.