Twitter had what you could call a nice golden age. But the problem is that there's just a lot of competition out there vying for the same consumers that twitter has their own business modeled around. Nearly everyone has a Facebook, and you can post a status update on a Facebook. Yeah, it's not quite as good for viral communicating as Twitter is, but it's become a big preference.
Here's a graph that shows the competition related to Twitter on usage statistics. As you can see, there's a lot of competing websites out there and Twitter is much lower on usage than Facebook is for general users. Another big problem with Twitter is that it's focused on the ability to 'tweet' 'retweet' and communicate in that manner but platforms like Facebook are very broad and more general purpose.
