Tempting was right: The debut of Fox’s critically skewered “Temptation Island,” the reality-based series that sets out to entice committed couples into being unfaithful, drew 16 million viewers, according to preliminary Nielsen ratings. That’s a good half a million more sets of eyeballs than tuned in to see the first episode of CBS’s “Survivor” last summer. Still, high as the “Temptation” numbers were, its NBC competition, the Emmy-laden “The West Wing,” did even better: 17.7 million viewers. Aye, but here’s the rub: the couples on the Caribbean island attracted a younger crowd than the folks in the White House. “Temptation” scored a healthy rating of 8.3 in the highly coveted 18-49 age group demographic, compared to a 6.3 rating in that demographic for “West Wing.” Meanwhile, in other TV event ratings, Ken Burns’s 19-hour documentary “Jazz” on PBS got off to hot start. The first three segments averaged 5.6 million viewers, more than double the usual PBS prime-time rating, says Nielsen.