I think it would be beneficial if it would be able to regulate and implement policies to existing exchanges and declare international standards for security and such before an enterprise opens up an exchange. This is to prevent thefts, scams, etc.
Having a central agency does not necessarily mean the system would be centralized. The supply/demand and block generation, as well as trades are still decentralized and controlled by the traders. I don't see a problem here. And also, it does not mean it would collect every single address owner and his details. It's just to have someone responsible to exchanges with unsecure platforms.
This is much more beneficial to crypto in general since most of the scams come from altcoins and various crypto-related projects.
(points 1 below is about exchanges/business. not the bitcoins themselves)
1. regulations(facepalm)
reguations give exchanges the ability to make their own policies on how to stay in the law, but then make it only a crime to disobey the law if they dont report it. if they do report it the only penalty is not criminal, but civil (a fine & resignation letter of a scape goat employee).
regulations give businesses a shiny sherriffs badge to police its customers
what should be promoted is not regulations but consumer protections. alot of people think regulations are consumer protections but they are not.
take the 2007 financial crisis. the bank bailouts, the consumers houses forfeited/foreclosed on. banks were regulated but consumers lost out.
banks didnt get slapped wrists(prison time) because they, when the crap hit the fan, reported their mishandling just intime before getting slapped for not reporting it should the crap hit the fan before reporting.
2. having a CENTRAL authority is centralising things.
a solution would be for instance, for those suseptable to scammers or just happily willing to throw large amounts of funds around without thinking that each person nominate 3 members of their family as co-signers of a multisig. thus keeping things somewhat decentralised. then if one person wanted to spend money. the family can check that person is sane or stupid, by asking if the person knows the recipient. thus family get to slap some sense into the person if they are about to make a foolish mistake handing funds to strangers(prevention better than remedy)
take eamples where scammers target old people that thy owe tax, unpaid bills and must immediately go and purchase itunes/google giftcards to pa the scammer. imagine if the granny had to ask families permission. and the granny told the scammer she cant do anything without family consent. the scammer would have just hung up and the family would help the granny come to her senses to not be fooled so easily (with a cup of tea not a slap)
3. no authority has the ability to reverse bitcoin transactions apart from the holder of the bitcoin deciding he is moral enough to hand back his ill gotton gains. to have a system where funds can be taken away by someone thats not the holder. EG an outside party who has no private key access to the funds. is not only bad security. but also ripe for abuse. such as police seizing funds without having the bank customers password/pin number. or seizing rolls of banknotes from a car stoppd at border patrol. because of no crime but just having more than what police deem fit that a person should have in their car. under the illusion that having too much money is suspicious
imagine the situation. no on is allowed more than 1.2btc or they will be investigated and funds frozen for having more than $10k in their possession