You people are funny...arguing over why the Robbie's have such wimpy restraints. So silly!
I *GUARANTEE* you that it worked out this way when Frankie R. was designing the R-22:
1. What type of restraint meets the letter of the law with respect to certification?
2. What type of restraint is the cheapest?
3. What type of restraint is the lightest?
To even fantasize that Frank was concerned with making a "safe" helicopter when he designed the R-22 is just ludicrous. All he was trying to do was make it as "safe" as possible GIVEN THE CONSTRAINTS OF THE DESIGN PARAMETERS.
Sure, we wish he would've given the cabin more structural integrity...or a beefier landing gear. Sure, we wish he had put in a four- or five-point harness. Maybe we should wish he'd stuck a three-blade rotor system on it! But he did not do any of those things. Why? Weight and cost, baby! Not due to a conscious neglect for ultimate safety, but the whole thing ended up being a bunch of design compromises.
As for seat belts, I've seen plenty of Bell 206 accidents where the belt assemblies pulled right out of their mounts - and the pilot lived! He was ejected, but he lived. In one case, the pilot was ejected through the windscreen and broke his shoulder on the centerpost on the way out, kind of adding insult to injury...or extra injury to injury. Made me realize that the strongest, most robust harness in the world is only as strong as the airframe it's mounted to. And in the case of the Robbie...
Given the choice, I would always prefer a full, complete five-point harness. But we are not always given that choice, are we? But as long as the particular restraints that are installed in the aircraft are properly secured and adjusted, any discussion about which type would be "better" with regard to a helicopter crash is pretty moot.
Finally, consider this: People panic. People revert to what they're used to. If you take a non-aviator and stick him/her in an aircraft with a restraint system that is unfamiliar, they absolutely will not know how to undo it if there's a crash. Heck, people can't do it even when there's *not* a crash.
I've had passengers who were distracted and eager to get out right upon landing for one reason or other (after flying with me, can you blame them?). First, they forget the belt and try to hop out. Then, when they realize that they're still "trapped," they search around frantically for the release mechanism. These are people, by the way, who've *all* flown before and have had the FAA part-135 briefings many, many times - including before that very flight. Yet they still forget. Usually I'll just sit there and watch them struggle. Finally, I'll say something smart-alecky like, "Gee, good thing we're not underwater...OR ON FIRE!"
So reassure yourself that you've thoroughly briefed and instructed your non-pilot passengers, if you like. But people forget. And in a highly stressful situation (like a crash) you simply cannot expect them to remember the particular seat-belt removal technique. ...Which is why it is probably better to have automotive-type seatbelts in aircraft.