Imo, it shows that, like many of us, they don't really understand why Twitter became so popular. That being the case, they don't know what they can and cannot safely change.
It is better for the reader, not so for the writer. Because of that, I do not understand why they focus so much on getting more writers (login) than readers (views).
"follow me at _ on Twitter"
That said, I think most comments are missing the point - having attachments not take up characters really won't make the service any more useful to the mainstream... That's the real problem in my opinion.