Let us not forget the other popular app of google's that remains in beta after four YEARS:
GMail.

When Google says "beta," they don't really mean it. I don't really know what their angle is about leaving things in beta forever, but it might have something to do with undermining user's grounds for complaining. That is the most common rebuttal by proponents of any software when it's a little buggy or otherwise flakey.

Mail outages, Mail not working right, messages lost?
"It's beta. What did you expect?"