Seriously, this looks like something out of a consumer/UI facing open source project with 1000 contributors. (My favorite example: The glorious spectacle that is the VLC settings dialog.)
The important ones like conventions surrounding replies are weird artifacts left over from the early days of the product. Twitter bottlenecks quickly in lengthy conversations amongst multiple parties and you really have to carefully respect the social dynamics it creates, or people will just block your rude self. If there is one place where the product could use revision, it's in improving average case conversation quality.
This is Twitter's blessing and its curse: It's a game we willingly play to communicate within its limitations.
Even the greatest artists have to paint within the canvas. By making the canvas ludicrously small, limitations become a democratizing force.