Twitter is not for everyone. Having said that...
HOW MUCH PROCESSING POWER CAN A COUPLE EXTRA MENU OPTIONS ON 2011 HARDWARE/SOFTWARE POSSIBLY TAKE??? Does anyone honestly think it would ever affect anyone? Ever? --like even one perceivable difference in speed ever? even once?
The reason some people express annoyance (mental anxiety) is because its a matter of neutral elegance. All those not on twitter read "deep integration" as crossing their boundary into their territory of neutrality, practicality, and optional hyper-simplicity of iOS. It almost comes off as inappropriate and in bad taste to implement something that they mistakenly/too simply perceive as pointless social galavanting that seemingly belongs in the realm of optional apps.
But its not just a bunch of malarkey. Here is why it is OK
Twitter, for news and culture, is just as essential as YouTube is for visual information and Twitter is the future due to its genius efficiency of raw information and is way "bigger" than Facebook, (which is now boring and serves more as a public online identity card with various levels of privacy) because Facebook is about Myspace-like social expression such as lifestyle, and pictures, and girls using real-life as simply an opportunity for a photo-op for their virtual identity on Fakelife where social upkeep has been reduced to a "news feed."
So while Facebook is about pictures, Twitter is about human thought.
Profound right?
Twitter is about news and human expression. Its about the raw building block of all art which is: everyone wants someone to hear what they have to say. Everyone. Whether they are in pain/denial/insecurity and rejecting/given up the urge to want to be heard or not. Since it is about artists then, it is very appropriate and in tune with the spirit of Apple

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Since it taps into such a core aspect of human need, Twitter will not only not go away, but will actually change the way people think and even learn, making everything more efficient and giving voice to the type of thoughts and knowledge and expression that would otherwise never be given a voice in any other less simple, less-efficient, or less-masterfully crafted system of content creation vs. consumption. The format is an essential aspect of continued participation of both creators and consumers. Its very handy and can be creatively used in many ways for many purposes because of its raw simplicity.
Yes celebrities have way more one-way relationships of human expression but that is not the point of Twitter. If you only have one other person; a friend, stranger, whatever, who hears what you have to say, then that is enough.
You know when you randomly have those awesome thoughts and you think, wow I should write that down and remember that later so I can say it to my friends? Well its like that. Now you just pull out your iPhone, and post it on twitter and everyone who follows you, can share your thought instantly.
The difference between Twitter and others is its simplicity, much like Apple, it sets it apart and makes people addicted to it and actually want to use it because of the deceptively simple (yet deep) principles of its design.
So in fact, Twitter and iOS are perfect for each other. Twitter is a revolutionary avenue of expression and I am curious to see how they "synergize" and evolve the art-form in the future.
follow me on twitter I guess

@friendlybuddie
http://www.twitter.com/friendlybuddie