The fact is that Robby's have limits. You can either accept those limits and have a happy career, or you can ignore them and die
But only the Robbie has had them added to (reduced speed envelope) following a series of accidents and a great deal of pressure from concerned aviators.
Is that really so? And what about the envelope restrictions that at some point were added to the AS350 Squirrel POH, meant to help pilots to avoid, detect, or get themselves out of hydraulics failure induced by a combination of high speed, high collective and cyclic pull? It is being discussed as we speak in a parallel thread right here in the Rotorheads Forum:
AS350 Astar/Squirrel
Immediate action if required to reduce the feedback loads [stemming from temporary hydraulics failure]: Reduce the severity of the maneuver ...
In maximum power configuration, decrease collective pitch ... before initiating a turn...
In hover, avoid rotation faster than 6 sec per full rotation.
I guess these are in itself serious limitations. At the same time, it seems quite possible for most normal missions to stay within the limited envelope and to never encounter the hydraulics problem. Clearly, Robinson is then not the only helicopter with design-related envelope limitations.
It is interesting to see that while here you say only Robinson had to limit the flight envelope, you are the main contributor to the AS350 limitations related discussion in the "AS350" thread. Both in one day.
I guess what we see here is actually quite normal. I could think of different, specific limitations applying to respective other types of helicopter.