By "cruiser",I assume you mean a actual motorcycle that people ride? It's easy to collect stastics. The NHTSA under Joan Claybrook mandated helmet laws for all 50 states in in the 70's,so the statistics ARE there to see. In fact,they were used as evidence to overturn the mandatory helmet laws in several states. Helmets save lives, the better the helmet the more likely you are to survive a crash.
Who told you this? Claybrook? Giddy Dolt? Your local Honda dealer who wants to sell you a big-buck helmet? The ONLY crashes a helmet MIGHT save you from are the ones where your head hits a glancing blow! If your melon smacks a telephone pole a solid blow at 60MPH,I don't give a damn what kind of cage you built around it,your brain is now jelly and your neck is broken. Ever seen the jelly inside one of these full-face helmets when it is pulled off the broken neck? I have. There is also the undisputable fact that you are more likely to HAVE a accident if you wear a helmet. They restrict your vision,impair your hearing,and are hot and cause fatigue. I know you might have a hard time believing this. So did I until I took a friend up on his dare and started to ride without one. Try it and see for yourself.
GP and superbike racers wear leather, kevlar and $600 full face helmets because they offer the best protection against injury, not because they give you more space for stickers.
They wear them because they DO make sense under those specialized conditions. Nobody is pulling out from a side street,there are no telephone poles or curbs,no horns blaring or other noises they need to hear,and in any accident they are likely to have they are usually able to "tuck and roll" so their head only hits a glancing blow. Their leathers are their real safety devices. What I wrote about smacking your melon at 60MPH is even truer when running at 120+ MPH. You ain't gonna survive a direct hit,and nobody is insane enough to even pretend you will.
At low speeds, jet setting about the biker bar scene and cruising the boulevard, that is perhaps arguable. Above about 75 mph, riding helmetless is painful, loud and extremely uncomfortable, especially on an unfaired bike - hardly a recipe for enhanced awareness. As for restricting vision, a properly fit helmet shouldn't, any moreso than goggles or sunglasses.
The sad part is, the no skid lid mafia is so powerful, and the fashion trend so influential, that wearing a helmet with your new EVO or VROD is tantamount to wearing a big pink shirt with DORK printed on it.
NHTSA, DOT and Snell Foundation statistics indicate pretty clearly that motorcycle accidents involving a helmetless rider are more likely to be fatal.
That certainly doesn't mean that a helmet will save you every time, but a properly fitted helmet does a better job of protecting your brain from severe injury than your hair or that cool skull & crossbones bandana - since the leading cause of motorcycle fatalities is typically severe head trauma, a helmets benefits far outweigh the risks, to your survival if not your fashion sense.