Well that depends upon your point of view.
In the vast majority of these instances, passengers volunteer to take another flight for some sort of compensation. Even when passengers are selected to lose their seat the kicking off has been entirely figurative. This was an extremely rare aberration. Shocking in it's violence, but by no means the normal process.
Congress could foolishly step in and put a complete end to overbooking. People with your point of view might fight this to be appropriate, but ticket prices would immediately increase. Do you think everyone would welcome that just as long as a one in a million incident that has almost a zero chance of being repeated can't happen again?
No airline, including United, wants to be the one who drags off the next beaten passenger just because they overbooked. If they didn't have policy and procedures in place to prevent such an outrageous act, they do now.
What should happen is the industry should voluntarily follow Delta's lead and increase the amounts they are willing to offer volunteers. Some passengers might try and take advantage of this, but their number is too small to be of concern. We buy airline tickets because we want or need to get somewhere. No one is going to get rich looking for overbooked flights, and the airlines are not going to, nor do they need to, make the rewards unlimited.
I'm pretty sure that United was within it's legal rights to refuse a paying customer a seat on that flight and that somewhere on the ticket it says so. Most of the flying public have experienced situations where flights were overbooked and it all worked out fine because there were passengers with flexible plans who were content with the compensation offered, and if not, they broke the bad news to the bumped passenger without breaking his or her face. If the doctor in this case had been treated a whole lot less aggressively, there would be no story to discuss.
Everything that could go wrong here did go wrong and United will pay a price, but unless the entire overbooking scheme is a total scam that doesn't actually help keep prices down, outlawing it would be very shortsighted.