If you just let contestants sit there and pass without penalty, the game gets really boring REALLY quickly.
Although it's another thing to keep overhead on, a limited number of passes (whatever the comfortable amount is based on playtesting) could be employed. Maybe even some strategery to save a pass for a higher value question.
Regarding the Split Second button-mashing strategy, if it was brought back today (it won't, but would be nice), it would be interesting if you had to lock in a selection. The second and third contestants would have the option of answering their original selection or any that were answered incorrectly. Kennedy format, too: selections first, question second.