Bloomberg terminals are multi-screen as standard, have a full window management environment, make very heavy use of the keyboard and shortcuts (I believe they are mouse optional, I’ve only ever seen them demoed with just a keyboard). These things are also only ever used on leased lines or very high speed wired connections to reduce latency.
The super fast trading is now mostly automated, so I suspect these productivity features are less important, and that a slick touch based UX could be better, but I think it would be tricky to convince people of that.
Why would a touch interface be better? The keyboard doesn't move or change state so you can type on it without looking (and your hands don't cover the display). You also don't move your hands so access to commands is extremely fast.
Touch is good when you have an infrequently used interface or when the set of data are highly unstructured (e.g. selection in a photo editor). Neither would apply to these cases.
What do professional traders do nowadays? My impression was it is already bots talking to bots and/or index funds outperforming/on par with actively managed funds.
Very untrue for the vast amounts that aren't -- ten thousands of different corporate and government bonds, thousands of leveraged loans, more fancy securities like convertible bonds, credit default swaps or contingent-convertible bank bonds get traded over Bloomberg chatrooms (think Whatsapp groups with lots of additional features but lots of regulatory red tape).
In these markets passive funds underperform active funds by vastly more than the fee differential - and that is not coincidental.
2) Human traders will generally trade products that aren't automated or will trade products that are automated in sizes that aren't automated. They will also oversee the automated trading.
Finally, at $99/mo you can market to "home-gamers" people who invest from home in a non-professional settings. Much larger pool of potential customers.