Biggest problem with that is that eagle holes change from tier to tier as the lengths, wind speeds and angles change. A hole that's relatively easy to eagle as a Pro might be almost impossible as a Legend and vice versa.
Outside of throwing in a few driveable par 4s, the Par 5 course we already have is as close as we're probably going to get to an Eagles Course.
It would be fun, though, if a player could construct his/her own practice course by selecting 18 holes and saving them like we can the equipment in the "Bag+". Buy a "Private course" in the Pro Shop and have fun building one for practice only. See how low you can go on holes you select yourself.