I really think that the biggest reason BBJ fighters have such a good reputation is that the techniques DO get practiced in a more realistic environment. You can grapple and do locks and chokes more "for real" than you can with full-power strikes to vital areas. It's all in the training and the attitude. The Gracies have done an excellent job over the decades making sure that their stuff works and making sure that the training reflects reality. The VAST majority of other arts can't make that claim.
Another poster mentioned protective suits...a great idea for strikers but it still doesn't give them everything that they need. It's basically impossible for someone to train in open-handed striking arts to the level that grapplers can train. You can't just gouge eyes, punch throats, kick knees and unprotected groins, etc. in a martial arts class. A striker ends up learning, at best, how to throw punches and kicks to areas which are actually NOT the best areas to attack.
The best instructors that I know teach thusly:
The first used to run classes in which several things were taught (no katas or anything "traditional"...this was a hard-core class). Physical conditioning was foremost followed by mastering the basic punching, kicking, and blocking techniques. Other things (knives, firearms, sticks, various "one-steps" or "street defenses") were after you had the basics down WELL. Full-contact sparring was done once a month. There was no protective gear other than cups, gloves, and mouthpieces. Other than that, it was about as close to a "street fight" as you could get. Cups were used more to cushion blows that were thrown to your groin than as protection in case someone accidentally hit you there (more than one cup was broken by groin kicks...ouch). Fights would go until one of the combatants couldn't go anymore. Bones were broken and blood was shed in this class. Needless to say, the school was not a commerical success, but it produced students who were TOUGH. As brutal as this training was, it still didn't allow a striker to learn and practice everything that might be done.
The second is/was a student of the first. He has broken things down even further and really teaches nothing but physical conditioning and basics (plus firearms). He sees no use for complicated aspects of the martial arts because he is a "no-nonsense" kind of guy. He doesn't feel that there is a NEED for anything but being able to land the hardest kick, punch, elbow, or knee possible to a moving, resisting, and/or evading target.
Neither of these men is anyone to mess with but the potential of what they practice is STILL not fully realized because you just can't cripple and kill people in practice. Both have fought BJJ and other grapplers and won and lost. In the losing cases that I have seen, the men have had the OPPORTUNITY to land blows on the grapplers which would have ended the fight but they could not due to the rules and just sheerly for the fact that the fights were friendly. You just don't shin a guy in the throat in a friendly fight.
I don't really believe in fighting multiple attackers unarmed. More than one guy and you're very liable to be beaten. Better to fight your way OUT of the situation. One on one, you would be better served to go with a grappling art because of the reasons that I cited above...the training is just FAR more realistic. Striking is fine but, one on one, you can always take the fight to the ground.
I'm sure that I'll getting flamed a little on this, but it's my experience and my belief. I love the martial arts, but learning anything complicated or anything that you can't train at 100% (or nearly) is just exercise for mind and body and not necessarily what you want if you want the best fighting art around.
My only complaint is that I can't find anything in my area where they train in grappling. Everything is traditional martial arts and people not fighting full-contact. If anyone can point me to someone in the northeastern Arkansas area who trains realistically, please do so.