The reason they keep changing them all the time is because the main purpose of certifications is to continue to make money for the certifying body IMHO. :-D
I completely agree. I have written some exams for 2008 R2 and I am an MCP. My personal feelings about these exams is that:
1) I did learn some things (but not many) from the material that I will use in the future.
2) I did learn some things from the material which helps me understand how Microsoft programs their software (not quite like a boss).
3) The mark on the exam is inconsequential to actual programming and problem solving ability.
4) If they don't keep giving us a reason to keep taking more exams, they won't have anyone taking them.
So, why did I wrote these exams? Microsoft Partnership Program. I wrote them so that my company could get a break on Microsoft software licenses. If getting a 2012 MCSA or MCSE of either kind will help my company, I will write them. And I will also be a marginally better programmer because of it. However, experience cannot be replaced with exams. I would take a quick learner who can problem solve and has experience over anyone with a list of exams beside their name and no experience.
It's all about the bottom line. And the bottom line is: those exams are almost worthless unless you are using them toward the Partner program to get free licenses from Microsoft.