Comment by jacobolus

You can have high information density and still not have words running into each-other. Taking all of the space out from around text and information graphics makes them less legible, even for experienced "power users".

I think the goal here is more an aesthetic of being for "serious traders only" rather than a UI optimized for speed and clarity. The UI designers probably have little choice but to match the preferences of the user group though, even when those preferences are empirically detrimental.