Is there any professional software that wouldn't benefit from high information density? Most software design is optimized for the non-users who have to approve it.
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.
Higher information density is ideal but when people are working in less than ideal conditions (stress, lack of sleep, alarms going off, etc) you need to prioritise information clarity and clarity of actions over raw density.
And yet, we make such beautiful and vacant software ourselves for our clients, because again, its b2b, so you aren't selling to the people who actually have to use the software. Im glad at least we arent forced that often to use specific internal tools, the better ones just get adopted organically
I guess JS doesn't have to care about this at all because they're not selling their UI to others, just making it in house for in house use
Think node, except the other direction. They write their backend in OCaml, and then they also write their web ui in OCaml with a translation layer
Or think of gwt (java) awhile back