Either:
It is cool. So we must use it.
Or:
Everyone else is using it so we must use it too.
Seriously:
140 characters? Feature?
Everyone can read everything? Feature?
The two biggest technical "features" of twitter can be arrived at by dumbing down either google+ or facebook 98%.
1. It's where the people are. I don't think anyone is 100% loyal to it, but you have to respect its reach.
2. Instant answers. I can get insight on news via Twitter well before I can get it anywhere else. On top of that, I can get it from the people I want, many of whom are Tweeting hours before they are able to get an article published. This is great for sports, politics, etc.
I personally don't use Twitter nearly as often as I once did, and I rarely find reason to Tweet, but I do enjoy browsing it from time to time.
Twitter on the other hand is full of interesting conversation, people speaking their mind, and great interaction and interesting insight. The amount of tech things I've learned from cool people on twitter is far far greater than Facebook.
Experience of both mediums prob depends on who you're interacting with. For me, Twitter is where the interesting people are.
Or as someone put it once: Facebook is for people you used to know, Twitter is for people you want to know.
I wouldn't use Twitter if it was limited to people I already know, for instance.
It seems to me that discussion is pretty much the opposite of inane.
On things like Facebook, discussions are mostly between friends or "friends of friends", with no chance of an outside opinion, for instance.
And anytime I've looked at anything remotely political, I had to take a bath afterwards
These are ultimately people they wouldn't choose to follow the conversations of at all, given the choice.
For me Twitter was like starting with a clean slate. I just follow the people I want to follow, basically no 'friends', just interesting people.
I use it for things like gaming, talking to locals (almost everyone I know in my current city I met through Twitter, or through someone I met through Twitter), getting local news, and keeping up with friends.