Freeing up the code space that is required for the stock display allows for more features to be implemented. The KD8CEC software also allows additional controllers to be added for things like spectra scopes, second displays, CW decoding, and others. There is also an S meter addition that uses the spare A7 pin on the Nano. Dr. Lee has also built an SDR interface into the KD8CEC software that allows you to connect an RTL-SDR like radio to the IF of the ubitx and manage it through the PC memory manager software that he also wrote.
It is a powerful ecosystem for the ubitx. I would encourage you to look through his blog at HamsKey.com
My opinions, yours may differ.