It's a sign of success that people are going Centurion out of the gate. For many troopers, going Centurion is not that much extra effort over EI, at least for some of the variations (folding stock on an EU trooper being an exception).
However EI is very important for existing troopers who need a path to pimp out their suits or future proof them. It's not just FISD, but in other detachments that what is today the EI/deployed standard becomes tomorrow, the base CRL. This happens perhaps every what - 5 years or so?
I would agree that the standards should really only change once a year at most, else it's too much of a moving target for our members. Ideally we'd back such a rule in to our SOP.