I've been working with people helping social media for a bit, and one common issue in preparing a list of tweets to schedule is making sure the length is ok. So you end up with silly xls files where you have a url column, a text column, etc. and weird formulas to compute the size.
I think Twitter just wants to simplify the life. You can send 140 chars of text/comment. Mentions, urls, images, etc. are not counted because normal people aren't counting like that.
Insane. For me it is the complete opposite. Having to read a personal conversation between two people is perhaps the primary reason I do not use Twitter. Far too much noise. And they should count hashtags as double (the other main reason why I cannot stand Twitter).
I tried using Instagram. Downloaded the app and created an account. It promptly emailed everyone in my address book notifying them that I created an account. Deleted the app and my account. Never again.
Twitter moves away from 140 characters, ditches confusing and restrictive rules
Submitters: please do not rewrite titles unless they are misleading or linkbait: https://news.ycombinator.com/newsguidelines.html
Please especially don't rewrite them to make them more misleading and linkbait. (Submitted title was "Twitter ditches 140 character limit".)
Because a few times I have left out the year since I couldn't find a good shorter title, and then you added the year afterwards. I would have done that myself. :-)
On twitter, I have thousands of followers and I'm lucky to get even one reply or mention.
On Facebook, however, I have about 300 friends, and I can post an actual paragraph along with a photo or a video. I often get 30 likes and 20 comments on the posts.
Facebook does a much better job of facilitating real conversations, and yet it still allows people to post 140 character blurbs (if they want to).
I get it though. Twitter is what it is, and there are tons of people who love it. I'm not one of those people.
EDIT: I'm aware of the original reasoning for the limitation, so perhaps "arbitrary" is not the best adjective.