Neither have I had a golden egg challenge either. The simple fact is that the King servers would have some kind of capacity limit. If it goes over capacity, then we have problems connecting etc. And that's probably why only a percentage of players get an opportunity each time.
I understand about the a/b testing but I thought part of that was to provide different groups of people the event so they get a wider spectrum of feedback, so I was hoping I would get it this time. Oh well - maybe next time. I did get a chance with a similar event in Soda.
Of course it makes perfect sense to see how popular the events are. The same thing applies to any goods or service that a company provides. Could you imagine if Hans Glas GmbH still made the Goggomobil?