Back in The Day, Hockey East teams would also play a 2-game series in the quarter finals, but the winner was decided by total goals in both games, combined. That was a curious arrangement by today's standards, but it made every shift count.
A team could win big on a Friday, and find themselves trailing on the next night... Ergo, neither team would concede an inch of the ice for either game, and would never throw-in the towel no matter what the score in a competitive series. When OT is on the table -if you split- sometimes teams just cruise and save energy in a lopsided game, waiting for another shot in a series OT.
Having said that, two games are better than one as far as comparative data goes. And it's interesting, no?