They need it to pick up the pace in the game.
From the NY Post.
“We will start getting ready for the possibility that we’re going to use the pitch clock on Opening Day,” Manfred said. “It’ll be a phase-in to get players and umpires used to it. But we’re still hopeful that we’re going to make an agreement with Tony [Clark] and the union on pace-of-play initiatives. Whether it’s by agreement or otherwise, the only prudent course at this point is to be in position to proceed if in fact we have an agreement under our collectively bargained right to do that.”
I think this is a good solid move to speed the game along.
Read more here