The character limit is, in my opinion, the primary reason Twitter became so bad. It encourages absolute language (qualifiers take up characters!) It discourages any level of nuance.
I use Mastodon which has a 500 limit, and even that sometimes is not enough.
What do you mean with "became bad"? It started out with a 140 characters limit in 2006 and kept that for more than 10 years. So its the other way around: it became worse, when the character limit increased. Though I don't think its due to the character limit either way.
The opposite of short exists.
https://tuhat.net/about
Also open source.