Speed is a fine thing, when you have alot of data to transfer. Developers do like the simplicity of legacy ports when it comes to basic communication with the uP. It remains the best way to get basic functionality during bring up, as well as examining registers, etc. All our products still have uarts and serial ports, as well as parallel I/O.
Add in ports are available, but we need to figure out how to access them. Heck, Hyper Term works with add-on ports, just as though they were native. We should be able to access them too.
Dev boards have interfaces to KM&M, maybe I should just use these in lieu of a PC.