This question is being asked a lot lately, as more sites and apps begin requiring the sharing of Facebook or Twitter information for login. While it used to be that you could choose to use this service and so socialize your experience, and otherwise do a regular registration, that is becoming less common by the day. Far more sites are going for Facebook or Twitter login choices only, which is managing to alienate a lot of users. In particular the users who fear for their privacy.
So, why are so many sites doing this now? The obvious answer is business related. It connects them to Facebook, which is a large company that many people like. It socializes the process, which is another big seller. Plus, it adds a bit of convenience for users, which will attract many more than it will put off.
Is This a Good Thing?
Recently, I saw this same question asked on Quora. The highest rated answer came from Robert Scoble, who said it was part of a trend of more predictive services. His opinion is that this is a good thing, and one that he looks forward to further progressing. He also pointed out the massive amount of data Facebook has about its users, and the potential for customization.
Not everyone agreed with him. Kaliya Hamlin stood out as a detractor, who made the point that Facebook having data they go on to sell to third parties is not necessarily the happy situation Scoble was making it out to be. Though she does admit that the ability to forgo passwords and so limit security risks is a positive.
Also note Facebook privacy and security issues by DirJournal web directory
In the end, your own opinion on whether it is right or wrong will come down to your belief or disbelief in a real identity system becoming prominent on a once anonymous internet. Something that Facebook has been very vocal about their desire to do. Google has also been trying to force this change, like on YouTube and Google+. Interconnectedness and transparency are now the name of the game.
This is not necessarily a bad thing. But providing the option to control how much data you share between sites is, to me, crucial. Those sites that are attempting to press users in Facebook or Twitter logins are doing it wrong. That is only this person’s opinion.