Why bend your elbows in freestyle? The very best arm stroke recovery is one which allows the hand to arrive in time to begin the next stroke but also allows the arm to slow almost to a complete stop just before the hand enters the water. Bending the elbow allows you to do this. If the hand and arm come forward and slam into the water, you lose momentum in the form of drag, and your arm fails to move you forward.
To get used to the bent or high elbow recovery, practice the Finger Tip Drag drill. Swim freestyle but drag your fingertips across the top of the water on each arm recovery out of the water.
Fingertip Drag is standard freestyle except that your fingers never lose contact with the water. From the moment your hand exits the water in the back to the moment it enters the water in front, the fingertips remain in contact with and "drag" across the surface of the water. This drill teaches a low head position, good rotation and a high elbow recovery.
This drill also teaches great extension out front and encourages a low body position. The elbow is the highest part of the body. The act of dragging the fingertips through the water gives the lead hand plenty of time to reach forward.
Furthermore, keeping the head low creates a bow wave. Because the head is low, the hips ride high, creating an efficient position that allows the body to glide through the water.