It's great on paper, but there are alot of risks.
What's to stop an old and/or terminally ill person for kidnapping someone, becoming a nothlit of them, then killing them?
What's to stop people from morphing the wealthy/famous, and becoming a nothlit? If five different Bill Gate's show up at the bank, how can they prove otherwise? DNA, fingerprints, all would be identicle. Asking for names of best friends or signatures and other given things can be faked; you can spy on/research a person and forge documents.
Then there's criminals. Say I just went skiing and became paralyzed from the waist down, and they give me morphing technology. Then I morph a rat, steal from stores and such, morph out, and keep the stuff. Or I morph a random person, commit a crime, let them get blamed while I take the goods. I could morph a person I have a personal grudge against, kill someone else I have a personal grudge against, and have one person dead and an innocent one in prison for life. It could also lead to a greater chance of violent crime and other violent risks; as long as you don't take a bullet to the head you can almost always escape undamaged. The same suicide bomber can blow 4 car bombs. Prisons would need to be changed dramatically; I could morph fly and leave, morph a guard and walk out, etc. (I guess the funding saved from hospitals can be used for this lol). Assassins in general would be much harder to detect (I could become an extremely lethal spider and kill the president in his sleep).
However, I am a strong supporter of innocent until provent guilty.
Take a gun for instance. Innocent people can have guns for the good, postive aspects of them (defence, security, hunting, sport, etc.) Guns stop crimes millions of times anually, prevent many deaths from crimals, and in over 98% of all crime prevented by guns, no shots were fired, the mere presence of said gun ended the problem before it started. There are many Olympics competitions involving guns. For many, it is the only way to put food on the table. (Shoot a deer legally, and you just got 100+ lbs of meat for free). Guns, however, can be easily taken away. If one has a criminal background, they can't legally buy guns and can have all previously owned guns confiscated. Sure, you can never take away all illegal guns, and criminals will always have them, but you can disarm alot of criminals, and still have the good population defend themselves.
Morphing technology can't be taken away or confiscated. You can force someone to become a nothlit, but no decent person wants a violent, criminal clone of themselves. I would say that if you reach a certain age and have a clean background, there should be no reason why you couldn't have it. Some people would be more willing to take risks or commit crimes if they would never get caught however. That shouldn't be a problem, however (innocent until proven guilty). The big issue is how to distrubute the power without letting it spread to the black market. Distribution would be very hard. It can't be private; what's to stop a drug lord with $25 million in cash from bribing the person. Even if it's federal and in ultra secure places, all it takes is a single stolen cube to be reverse engineered, and a week later you have a small army of rhinos destroying the city.
If, however, there was a functional Anti-Morphing Ray, everything could be simple. A gleet bio-fliter type anti-morph screen could be put in all secure locations, etc. The problem would also be if this got out, what's to stop people from demorphing people in flight? Or for torture, make people morph small, put them in a box, and demorph them. It's use for defence would be useless, a criminal could easily demorph anyone trying to save themselves, and soldiers would have no use; the enemy would also just demorph them.
Still, I'd definitely be pro-morph in a vote. You can't take away from the innocent based on what criminals might do. The benefits dramatically out weight the costs. You can't argue saving the lifes of millions annually. Not just injuries. Cars? Who needs them? Fly to work. If everyone in the nation didn't use a car for local transit, think of the financial and environmental impacts. It would be phenominal. Starving people? Morph an herbavore, eat some grass, demorph. It isn't a permanent solution, but it can hold people over. (Don't say you can't, the ani's did it in book 25, they morphed wolf and ate a seal as to not starve). Billions of dollars would be saved anually for medical. Car crash, broken leg, it all can be saved. Lost in the woods? Morph a bird or wolf and get back home. Drowning? Morph a fish. Choking? Morph something big. Sad? Morph a dolphin. Dark? Morph a bat. Lost your shirt? Morph a dog and sniff it out. A cop can morph his own bomb/drug dog. When I say this I'm serious - The amount of lifes saved, the damage prevented to the environment, and financial gains would be massive. It would almost single handedly save the world without exaggeration. Most disease and injury gone. Carbon emissions from most car travel? Gone. Massive medical bills? Gone. Fireman horribly burned saving lifes? Gone. Living as a cripple? Gone if you weren't born that way. The effects on knowledge would be huge. The best way to know about animals is to be them. The overall gains would be incredible.
It comes down to the simple fact, are we willing to take risks to incredible gains?
Also it comes to the fact, when we we spontaneously increase our technological knowledge by thousands and thousands of years?