SASless,
There are engineering checks to be performed if one exceeds an MMI limit, therefore I believe that the MMI gauge was always destined to be in the production aircraft.
This theory is further supported by its appearance in the BK117 and the EC135.
I concur with helmet fire, that it's quite the show if you can ever spare an eyeball to check out the MMI during a running landing. Although these days, if running on in a 135, you'll get the bong if the surface is too rough!