I think it's time to rethink the 140 charcter limit.
When people want to post more than 140 characters, they include it as an image (so not searchable), which is considerably more effort.
Why not allow longer tweets, and only show the first 140 chars by default (along with an indication of how long it's going to be), and then load or show the rest on demand?
Because I mostly don't want longer text from people. Twitter forces people to be concise. One of my favorite things about Twitter is the large number of voices I can follow. More text per person means less voices.
That said, I think they could do it successfully if text were treated as another media attachment like photos or videos or links. People would still have to write a concise ~120 character intro; if I wanted more I could click to expand. But making main posts longer would be a great disappointment to me, possibly enough to kill my use of the platform.
It's impossible to have meaningful conversations with that kind of limit. You end up having to use "1/N" over and over again. That limit has always left me wondering how Twitter even got started...
It actually got set like this because tweets were originally sent and received via SMS, which has a 160 char limit. The additional 20 characters were reserved for twitter metadata.
What you're saying is inherently incorrect. "Usefulness" of content is always going to be more limited by 140 characters than it would otherwise be.
It worked, not because people want to "share" less, but because they want to read less. Same reason a lot of people browsing Reddit for example only browse it by glimpsing the headlines. The more news there is, the less people are interested in the details of the news - they want to let their brains fill in the details.
Say, for example (and please don't read too much into the example), you read an article that says "Police shoots an innocent civilian". Then a few days later, you read another article very similar to it. Then another. At some point you stop reading the article and you just glimpse the headline - filling in the details yourself, even if they are wrong. You do this for every article you come across, and you enter a cycle where everything you read ends up fitting your own learned narrative. Your brain autocompletes the content of every article... and if there is no match, you can just ignore it.
This sort of behaviour is something you see a lot of on Reddit. People are attracted to short snippets of information they can autocomplete. Most don't want to spend a lot of time on something they might be reading on the toilet, or on the subway. It's the same reason mobile toilet games are racking in millions, while the PC gaming market is taking a major hit.
The 140 limit is a feature, not a bug. The character limit places the burden on the sender to compress their message, instead of forcing the receiver to read more. Shorter messages = faster reading = faster replying = a more active network.
If you're interested in a service exactly like Twitter but without the limit, take a look at GNU Social - https://gnusocial.no. Granted, it's mostly developers on there, but Twitter was similar when it started.
When people want to post more than 140 characters, they include it as an image (so not searchable), which is considerably more effort.
Why not allow longer tweets, and only show the first 140 chars by default (along with an indication of how long it's going to be), and then load or show the rest on demand?