That is probably part of it, although this time the owners insisted on expanding the playoffs specifically because they already had a new playoff deal lined up.
The problem is if you have too many teams in the playoffs, all the good teams will clinch in August and can coast the final month which is not exciting for fans of good teams.
Then the post-season in baseball is such a crap shoot that it becomes almost meaningless.
The end result is that it's not necessary to build a great team when being pretty good can reap the same rewards which is the player's concern.