The universe is expanding exponentially. The universe has to expand like that, otherwise it would not exist. So I really don't think it has a choice. If the acceleration were slowing, it would mean the universe is reaching a certain "point" or value. 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-pinable/undefinable rate. Anything that could be defined/define the universe as arbitrary would cause it to cease existing.