Yes, that is the goal. It's not even that difficult. (I'm pretty much a beginner at IS stuff, and I can do it.)
For mobility. agreed
Once you're stable in a shoulder-width square stance, being stable in hamni is relatively easy. Then the challenge becomes keeping that stability as you move.
I am taught that your body should learn correct posture/stance and mixing styles would seriously interfere with that. For instance, mix karate and Aikido. the stance is completely different, how would your body know what to do? Muscle memory gets confused....