To begin with, it would be much easier to implement an even-numbered court than it would be to enact term limits. Like past Judiciary Acts, it would take a simple act from Congress. Term limits, on the other hand, as many of its proponents concede, would require amending the Constitution. Term limits could take decades to fully implement.
Court-packing is even more troublesome. Although it would require only legislation to expand the Supreme Court, doing so would invite nearly immediate political retribution. Like the elimination of the filibuster for judicial nominees, it is not difficult to see how Senate Democrats pushing for an 11-member Supreme Court would soon balloon to a 13-member Court once Republicans retake political control.
Importantly, an even-numbered court does what other plans do not: Takes more political controversies away from the court and gives them back to the political branches where they belong. In the case of a 4-4 tie, the court issues no substantive opinion, effectively affirming the judgment of the court below. The case does not set a nationwide legal precedent, and the law is the same as it was the day before.