1) SS has rules for breaking down a monster so why do it.
There are all kinds of helpful books out there for DM that try to save them time by designing places, encounters, etc. You could even argue that monster books are nothing more than an aide to save DM's time.
2) I would rather have my own version than what a publisher does.
Just because the publisher does a version of the breakdown does not mean that a DM can not alter it to suit their needs. Do you never change a module to suit your campaign?
3) Publishers other than WOTC can't do it until it is in the SRD
Well I am not an expert but I don't see why other publishers could not do it, as long as they didn't follow the rules set down in SS.
After reading the replies so far, my own opinion is that it would be a great web enhancement for publishers to do. This avoids "wasting" space as some would say while still providing ready made details for those what wished to use them.