• Smorgasboard of relatability: The odds are stacked against even the most cynical of TV critics to not find somebody to like. Even if, like me, you stopped caring about Lost‘s Jack/Kate/Sawyer triangular affair 10 episodes ago, you’ve got at least two more noble/tragic heroes, couples like Jin and Sun or Claire and Charlie to empathize with/root for, and lots of peripheral conflicts.
• Logistical safety net: If Masi Oka suddenly feels like his salary needs a 300% upgrade (not that he seems like that type, just as a what-if) and NBC disagreed, Heroes wouldn’t necessarily be ruined. Writers have lots of other characters and plotlines to both shift the weight onto and use to explain the disappearance of said ornery instigator.
• Corpses give good water cooler: Need a sure-fire way to get TV guide, Entertainment Weekly and TV-savvy blogs all atwitter about your series? Off a character nobody expects to go, or maybe perform some Darwinian cast adjustment by showing less-liked figures out with a somber burial scene.

But, as Slate points out, only a few shows are agile enough to make shows with big casts feel like big drama instead of thinned-out soap operas.

Nearly all of the women I live and work with have expressed dismay at how Grey’s got a little too “shocking development” for its own good. If you constantly toy with and reinvent every single character with unexpected negative traits, who does that leave to empathize with or, well, like?

How The Wire pulls this off is its own post, but I’ll say quickly that while the series benefits as a whole from long character development arcs, each episode can stand as a self-sustained entity against a clearly-drawn Baltimore backdrop.

Watching Lost, however, has occasionally felt like trying to find a file piled somewhere in the corner of a mountainous desk. I find myself forgetting entire aspects of characters that haven’t been brought to the fore in a while, or else questioning why characters are acting so strangely (“Wait, why is Hurley suddenly fine with The Numbers, but used to be crazy-scared of ‘the curse’ before?”). Trying to reconcile those kinds of thoughts in my head while the show plays, of course, somewhat lessens the sheer sense of fun I found early in the series.