You seem to be suggesting that offenses will be better because we move the 3pt out or am I missing something? If that were the case, wouldn't teams have figured that out already and just be doing that anyway.
It doesn’t matter what teams did before. Assuming the offense uses the 3 point line as a measure of spacing, closing out to the old 3 point line was closer than what the new one will be. You are forced to show your defensive priorities a bit more as you choose which areas to cover.