Yes, 800s at mile race pace would most definitely require full recoveries, for the exact reason Chris pointed out. You'd be running a mile at mile race pace with relatively short recovery by the end of your second repeat.
If you're doing your 400s with 1:00 recovery in 66, that's a big step to do 800s in 68-69 pace regardless of recovery.
As for paces of speedwork, you're trying to train different aspects of running, whether energy systems or neuromuscular systems or something else. In order to best train these different systems, you have to train at paces faster, slower, and equal to race pace. One (admittedly non-scientific) way of looking at this is if you can train yourself to the point that 2 mile or 5K race pace feels comfortable, that's going to make mile race pace feel that much easier and allow you to finish your mile races strong while everyone else is tying up.