Ok. I actually understand electricity. And I can't think of a reason.
Ground IS important. You can have a ground loop so how you ground can be important. but which hot leg you use isn't important.
I ran two circuits to my system, one on each leg. I do keep my system all on the same leg and plug other things into the other leg but that is really just a local thing. Once it goes back to the panel, all bets are off.
Jerry