Another thing that makes the tenpin both a challenging target and a relevant one is that when hit imperfectly, they will roll at unpredictable angles, forcing you to track them while firing if you want to salvage a good time/score. You just don't get that with any other target system, even a $100K video simulator.
As some have noted, top quality eye protection is a must. At Second Chance, they found anything smaller than 00 buckshot bounced back. Even double-ought did so occasionally. I learned to wear my Second Chance Kevlar groin guard when shooting the shotgun matches. Any bullet can bounce back if it hits the hard butt end of a downed pin wrong. One Iowa shooter lost a testicle to a bounce-back from a pin (giving new meaning to the old phrase, "I'd sacrifice my left nut for my favorite sport") and a lady in Washington state, shooting light .38 Special loads with her eye protection down at the tip of her nose, lost an eye to a bounceback.