why is there no voice prompt feature for the workout app anymore.

Prior to WatchOS 4 it most certainly did. During running using the workout app you would get distance, time, and pace voice feedback. You could adjust this for miles or km prompts. Using the Nike app and Runkeeper did the same. Neither of the three apps now do this anymore and you have to rely on the watch giving you a tap so you can look at the screen. Half the time you don’t feel the tap during intense running. Would most definitely prefer that feature to be made available again.