As “Night at the Museum” races toward $240 million in U.S. receipts and “Norbit” packs in the box office poundage, TV programmers can only look forlorn and mutter, “What about us?”In some respects, television is seemingly already well on its way toward a comedy comeback, at least in qualitative terms. “The Office” has restored creative glory to NBC’s Thursday night, “30 Rock” has won more than its share of critical plaudits, and the Peacock net’s upcoming Conan O’Brien co-creation “Andy Barker, P.I.” is an old-fashioned hoot, with Andy Richter playing a Walter Mitty-type accountant who becomes a reluctant detective. Throw in CBS’ “How I Met Your Mother” and “The New Adventures of Old Christine,” Comedy Central’s goofy “The Sarah Silverman Program,” FX’s uneven but occasionally quite funny “It’s Always Sunny in Philadelphia,” Showtime’s “Weeds” and HBO’s “Extras” and there is, once again, clearly something to laugh about. But for TV executives who operate in a world where quantity matters, there’s just not that much to smile about. Why aren’t good comedies attracting bigger crowds? The culprits are many, but some of the blame doubtless lies in the intensely personal nature of what people find funny, transforming TV into an embarrassment of niches. There’s also an argument to be made that part of the downsizing can be attributed to the technological fluency of the YouTube generation, which is growing increasingly accustomed to consuming their smaller-screen comedy in bite-sized bits as they slack off from studying or work. Whatever the cause, most of the shows mentioned are at best modest successes, and the network series that helped jumpstart the quality wave, Fox’s “Arrested Development,” tellingly had its run arrested, finally succumbing to poor ratings. And while a few hourlong programs that bill themselves as comedies have developed sizable followings — specifically, ABC’s “Desperate Housewives” and “Ugly Betty” — there are no half-hours drawing anywhere near the tune-in amassed by the dramas “Grey’s Anatomy” and “CSI” or reality shows like “American Idol” and “Dancing With the Stars.” In terms of a big, broad audience, CBS’ traditional sitcom “Two and a Half Men” remains TV’s most-watched half-hour, and its new companion “Rules of Engagement” has gotten off to a promising start. Again, though, that’s a lonely island among legitimate hits, especially compared with the days when “Roseanne,” “Seinfeld” and “Home Improvement” towered over the ratings. In fact, except for “Men” and the two CBS series that have followed it, no comedy is averaging more than 10 million viewers this season, including “My Name Is Earl,” which — briefly heralded as comedy’s potential savior — has done fine since moving to Thursdays, but isn’t heading any lists of the Nielsen variety. Unlike feature films, the high-concept TV comedy has mostly fizzled, including ABC’s stabs this season with the building-toward-a-wedding “Big Day” and building-toward-a-robbery “The Knights of Prosperity.” Then again, that’s nothing new when you consider the unassuming loglines associated with hits of recent decades: Six single friends in New York; four self-centered friends in New York; a blue-collar family struggles to get by; a doctor and his lawyer wife raise five kids; barflies hang out together. Compared with bold dramatic premises such as “Lost” or “Heroes,” comedy presents a formidable marketing challenge, which invites a few tough questions: Will the cycle turn yet again, as many have (perhaps wishfully) predicted, thrusting another right-place, right-time sitcom back atop the ratings? Or has that cycle already begun with the first-rate comedies cited, which simply thrive among smaller sectors of the viewing public? In short, is it time to reduce our collective expectations and settle for just-OK — relegating the mass-appeal, blockbuster sitcom to the historical scrap heap, as dated as “The Dick Van Dyke Show’s” Rob and Laura visiting dreamland in separate beds? Hope still springs eternal, because it only requires one breakthrough to put such skepticism to rest. The good news is that various networks have demonstrated they haven’t forgotten how to make audiences laugh, so who knows? If they can keep loyal core audiences chuckling long and loud enough — until others begin to wonder what the fuss is all about — a few TV executives might again have reason not only to laugh, but to smile.