There are a lot of mixed feelings out there about Twitter testing the new 280 character limit.
On the one hand you have those who feel 140 characters defines Twitter, makes it what it is and keeps it simple. Alternatively, there are those who have been calling for an increase for ages.
Aside from the whole "Twitter is 140, 140 is Twitter" thing, the most common argument in favour of retaining the lower limit is to standardise the stream, to keep "stream units" consistent.
But this is a hollow argument.
Embedding images, videos, various types of "cards" in tweets, and quote tweets - not to mention Twitter's own native ad units - has meant that the notion of a standard tweet or unit has not been a reality for ages.
It seems strange clinging to the idea that tweets are all presented uniformly when this doesn't reflect how the stream looks or works, and hasn't done for years.