Personally I don't see why it's needed (and people saying "of course it's needed don't convince me WHY). However I do not claim to know all the ins and outs of it so whatever.
The one thing that I do know is that it will FEEL odd, weaker. Even GC said that when they first tried it - the didn't do it then because it felt wrong. I know everything else is getting nerfed to match so our characters wont BE weaker but they will FEEL it (at least to some - I think a lot - of people).
As an analogy, take a sport like motor racing. Many people find it very exciting. The high speed is that turns them on to it. But what if it was slower.... It would be safer! Why not make ALL the cars not able to go faster than 30mph. There would still be the competition... there would still be the tactics...... Everyone would have the same nerf... so would it be as good? Definitely not! Nerfing everything together doesn't stop it being a nerf.
I don't know if its needed or not... but I don't look forward to it.