“Isn’t It Romantic” gets by, barely, on its apparently inexhaustible comic premise, and on Rebel Wilson’s stand-back-world-get-offa-my-runway comic chops. Why isn’t it better? Realizing it’s easier to review the thing than to make the thing, I ask nonetheless. Why?

For many the answer will be: It’s fine! It’s not much, but ... It exists to be liked. And it is time we saw a broader array of performers, and body types, inhabiting this particular genre. Last November Wilson, on “Ellen,” said she was “proud to be the first-ever plus-sized girl to be the star of a romantic comedy.” This was news to Queen Latifah, among others, and already you’re getting into debates about what constitutes plus-sized. Also, isn’t focusing on that one aspect of a movie, or the dress size of its headliner, playing into the wrong, regressive hands?

From the beginning, these movies have typically been the province of the rail-thin and the archetypally movie-star-acceptable. “Isn’t It Romantic” shakes it up a little. But this jokey treatise on the genre’s alluring lies is a 15-minute sketch, taffy-pulled out to 88 minutes.

It’s one of those “adorable concussion” movies. A Manhattan architect whose work life is all about being exploited by others, Natalie receives a blow to the head and suddenly she’s the star of her own candy-coated rom-com, set in a fantasyland version of New York City.

Suddenly the hunky, smarmy client (played by Liam Hemsworth) is hers for the taking. Loosening up and enjoying this new world, however, isn’t easy. According to the unspoken rom-com rules, Natalie’s best female friend at the office (Betty Gilpin) turns into her pointlessly competitive enemy. Her best male friend (Adam DeVine), who has thwarted his own romantic designs on his cynical friend, meets someone (Priyanka Chopra) who seems like The One, but of course he has already met The One — Natalie.

“Isn’t It Romantic” directly references “Pretty Woman,” a lot, along with “The Matrix” (these are not daisy fresh references). Brandon Scott Jones plays Natalie’s stoner neighbor in the “real” scenes, and her faaaaabulous gay stereotype bestie in the wonderland portion, a more outre version of the Rupert Everett turn in “My Best Friend’s Wedding.”

The two full-on musical numbers suggest a road not taken. Wilson and DeVine, especially, are great fun to watch when they’re singing and dancing. Had “Isn’t It Romantic” turned into a full-on musical, the contrivances and tired, vaguely patronizing messaging would’ve been easier to ignore. And seriously: What’s up with the concussion trope? Amy Schumer: concussion, followed by weirdly humiliating and newly acquired self-confidence, in “I Feel Pretty.” Taraji P. Henson: concussion, followed by new mind-reading skills and a come-to-Jesus reckoning for the Type A workaholic, in “What Men Want.” At this rate, audiences are risking head injuries of their own just watching these movies.

Director Todd Strauss-Schulson works from a script by Erin Cardillo, Dana Fox and Katie Silberman. All parties involved know they can get an audience on their side just by piling on the ritual slights and humiliations, with the Wilson character as the target.

Michael Phillips is a Tribune critic.