Dumb question as I think it needs to be a little more clear in the OP. Are you saying ppl should temp unroot, or NOT temp unroot using Rootkeeper before updating. I've seen to many posts on the leaks not being clear where some say yes do it & others say no just protect root. Speaking for myself to date in any of the files I have tried/tested I've never temp unrooted. I just protect root using Rootkeeper and then update and have not had a problem.
There have been claims that not temp unrooting causes the process to fail. After 100+ flashes and never temp unrooting I can tell you that temp unrooting is not what is causing people's problems.