The universe is expanding exponentially. The universe has to expand like that, otherwise it would not exist. It really doesn't have a choice. If the acceleration were slowing, it would mean the universe is reaching a certain "point" or value - even asymptotically. And any point is arbitrary making existence "unsupportable." Arbitrary cannot exist on its own. There is no reason an arbitrary value should exist while another does not.
Even expanding at a specific rate is arbitrary. It has to be accelerating at an un-pinnable/undefinable rate. Anything that could be defined or defines the universe as arbitrary would cause it to cease existing.