Don't forget that the trick to interface so many exchanges is that you must create a layer
MAIN PROGRAM <-> API LAYER -> External Api Sistem
When
MAIN PROGRAM doesn't know anything about the API LAYER. Nothing in specific. Only the Interface the API Layer must respect.
Sure, we already have it this way
But it takes time to come up with universal approach to cover all the little differences. For example, one exchange returns the list of executed orders from any desired day, another one returns only one month-back and for the lengthy strategies you have to sync your history. Little differences with various limits: minimum order sizes, minimum-maximum prices like on btc-e, number of digits after the comma, commission (absolute value versus percent), handling of partially executed orders... Anyway, we have resolved most of these issues and we made something really stable and universal.
But 24APIs - you are a Maaaaan! Honestly, I praise your patience!
Have you ever looked outside the crypto-trading? Like commodities, options?
I could easily mention a few cases when this approach can lead to losses
Or less profits, for that matter. Imagine a situation where your bot is placing a new order, and at the same time it analyzes in parallel data streams (which you yourself mention). Then it sees that the market quickly changes, but it has to wait until this order gets placed (or does something else which requires waiting), and thus not being able to do anything with other orders (at the same exchange) may cost dear. For example, it sees that it is profitable to buy or sell some other coin at the exchange due to an arbitrage opportunity springing up that lasts only a few moments (just enough to place another order). These orders may not even be related to each other. If the bot were running asynchronously (and the exchange accepted asynchronous requests), it could send a new order immediately and grab the opportunity. You see, 1 second may be an eternity within which fortunes can be made as well as lost
It's all about implemented trading strategy! In our case speed is not of the great importance.
Depending on settings (mainly risk and greed), trading cycles on some pairs may take minutes, while others may last for weeks.
We have a gentleman-bot who walks less because he plans better
You know, its like comparing a machine gun against a sniper rifle.