In this post I argue that the 140 character limit has not so much to do with the fact that such short texts are fast and easy to read. Neither that it limits "chatty" comments. Rather, I think it has all to do with the visual flow. 140 characters allow to display content in boxes of very similar and regular size, and it allows to display a flow even on smaller mobile devices.
So let's discuss first how I discount the importance of text size:
- To get around the short size, people are using all kinds of hashtags, using lots of abbreviations, squeezing punctuations. That makes tweets actually hard to read. For a matter of facts, I often see people not familiar with Twitter looking at my timeline and saying "I don't understand what they write". The keyword here is obfuscation. Sure, when you're using Twitter a lot, that helps, but for the average user, that makes tweets no faster to read that longer, but clearer ones.
- Is 140 character a sanity limit against too chatty people? Probably not, they write just much more tweets to compensate (You're probably in the 10% if you know that story from 2009).
So now why has Twitter been so successful? I'll argue that its decisive advantage against Facebook and MySpace is the visual design. More specifically, it's table design. In short, Twitter is like Excel. And it's no coincidence that Excel is still one of the most popular software out there.
Table are quick to proceed, and an extremely efficient way to navigate through information - even if it's text. You can also see that with the popularity of the table in HTML since it's early days. If tag clouds were more efficient to parse, they would have dominate the web. But they are not efficient, so they stay as a neat gadget out here.
In current visual design, grids are everything. And are the base for visual consitency. The iPhone resolution is based on the grid that widgets based on. So it's really rooted into the device.
So now take a look at those screen captures:
This is Google Plus. I can only see one and a half post, and those are relatively small ones. Some post may cover many screens. Also the bottom bar is taking up more space.
This is Twitter. Despite two posts being very near 140 characters, 4 tweets are fitting on one screen. There is a difference in height between a one liner and a full 140 characters tweet, but it's not that big.
So if your goal is to follow quite a big quantity of different sources, Twitter is definitely more efficient, because it enables such a fast raster between tweets. Google is more seeking depth and content richness, which is fully ok, but in my opinion the reason Twitter is not going to disappear yet.