Just watched a really cool video talking about quaternions including the story and this bridge!
Quaternions has other advantages as well apart from no Gimbal lock and less computational time.
It also has better keyframe representation:
keyframes in 3D animations mostly contain 3D rotations. Interpolating between these keyframes is very important. Using Slerp Quaternion interpolation causes good results in interpolating between two key frames. Actually Slerp selects the shortest arc in all possible paths in the rotation space (a 3D sphere with a radius equal to the magnitude of the difference of the source and destination points) to rotate one point to another and this is what we need most of the times, specially in character animation. The video link below shows the difference between 2 interpolations. The box on the left side uses Euler XYZ and the one on the right side uses Quaternion selrp for rotation interpolation. Both of them use 2 similar key frames.