Because they're a mess; the code needs sorting out, to move forwards.
It's like improving a building, like a train station or something; you have to knock parts down, make a hell of a mess, and cause quite a lot of disruption...but it's worth it for the future.
"Do you just want all of our maps and creations to be broken?" - For the greater good - sure.
Your wording is horribly biased. It's like saying, "Do you want your life to be disrupted for the next month?" instead of "Do you want a modern train-station with enough capacity for the next 50 years".
The changes are just small petty things such as m -> game mode, r -> distance, etc. All of this just simplifies things so that it makes the commands easier to understand. However all of us who use commands have already learned everything. I don't see the "mess" that everyone is talking about, I've made lots of huge contraptions from anti combat log systems to working rentable housing. I've never had trouble with the "mess".