As a journalism and media studies major with minors in psychology in digital communication, I found your article rather interesting and definitely of subject matter that I would personally further explore. I agree with many of the points you made, and overall, I do feel that Twitter has become the most practical social networking site of them all, combining features of other sites. But, as you mentioned, it, and heavy reliance on social networks in general can cause alienation.
You point out that Jessica Lawrence has concentrated her use of social media to primarily Twitter, while her Facebook and LinkedIn accounts are barely used anymore. I actually made my own Twitter account about two months ago, and now realize why some people are so hooked on it. Rather than having to load each 'friend' or 'contact's' profile, or filter through a newsfeed or homepage, everything is right there on Twitter for immediate viewing. Probably best of all, with the 140 character limit for tweets, everything is concise and right to the point. And as we know, nowadays the mentality of everyone is to have access to everything instantly, the faster the better.
You also point out the ways of linking social media accounts together, making one post appear on several sites. While everyone may not use solely Twitter, or be just a Facebook user, this feature could be a positive one, allowing one person to reach a larger audience in a shorter amount of time, without the hassle of having to log on to multiple sites.
You also talk about how social networking can lead to alienation. Like several new forms of technology, people are becoming so reliant on these recent internet trends, and I personally feel that they are hindering communication skills. Some use Twitter for practical reasons, checking the news, writing a quick message to a friend, or connecting with others about common interests using hashtags and trending topics. But what's too far? You give the example of spending time with someone in a restaurant rather than sharing it with others via Foursquare. Yes technology allows us to share just about anything, but, people also need to enjoy the moment, and not worry so much about being in a rush to tell others about it.
Thank you for reading my post,