At the very least this rule change will reflect how I imagine a decent sized portion of people have been (incorrectly as per current rules) playing certain cards and triggers involving their commander.
Though that might change the discussion to whether people are learning format specific rules before playing, etc. Maybe this is something WOTC could look into when printing the yearly pre-cons? I just looked at the insert from one of this years pre-cons and it only mentions that you have the option to put your commander into the command zone. Doesn't outright make the case that it is a replacement effect or what that entails (aka it doesn't die, etc).
I guess we'll have to wait and see what the implications are. I've heard that the rule change now means we place our commander into the graveyard or
exile first, and can then move to command zone (as opposed to moving directly to command zone). This is part of the spell or ability resolution, so no one can instant speed "yoink, that's mine now" in response. However, if a card said to destroy all creatures and put a creature killed this way into play, someone could indeed steal the commander from you as part of the resolution. I've also heard people talking about Roon and using his ability to
exile a commander then stifling the trigger to perma-strand a commander in
exile.
I'll wait to hear a more detailed explanation of the rule change to be honest before I freak out.