John takes exception to something somebody said somewhere (actually, it was a producer from 24, in a Slate interview) about the popularity of serialization and ongoing storylines on TV series these days. John lists, as evidence, the most popular dramas on TV and notes the lack of story arcs or serialization on them.
Now, I haven't watched all of these shows, but I do have to point out that the CSI series, while generally self-contained from episode to episode, actually do feature story arcs on a regular basis. Those series tend to keep their story arcs well in the background (and wisely so, avoiding the mistake many such shows make when they allow the soap opera to overwhelm), but the arcs are most definitely there: Gil Grissom's struggle against deafness; Catherine Willow's coming to terms with her own past; and others. CSI: New York seems to have the least, in terms of story arcs, but there are a few percolating away once in a while; and that show is offset by CSI: Miami, which has tons of arcs going all the time, including one giant set of arcs, potentially constituting three "trilogies" that will each unfold over three seasons each, about the past of Horatio Caine.
Sitcoms of today also tend to involve continuity, if not actual serialization and story arcs. Frasier and Friends led the way -- maybe even led by Cheers -- and that torch is carried on by Joey, Scrubs, Will & Grace, and more.
It's certainly overstating the case to say that every show these days involves story arcs and serialization, but it's a most definite trend. (I haven't watched Without a Trace, Cold Case, NCIS, or Criminal Minds, so I can't comment on whether or not those series blend arcs with their self-contained procedurals.)