It’s the run-up to Tony Award time, and entrenched Broadway wags are once again raising their voices in unison, singing the same old reprise, taking it up a key with each chorus: The Broadway musical is doomed, hopelessly degraded by the devolution of its subject matter.

“Shows based on known properties are mounting an offensive on the New York stage,” ran one doleful newspaper column, “and some in this old guard worry a sacred American institution — and a time-honored way of doing business — is becoming endangered.” Another columnist seemed suffocated by “the air of familiarity … pronounced among new musicals,” as all four of the Tony nominees for best musical — “The Band’s Visit,” “Frozen,” “Mean Girls” and “SpongeBob SquarePants” — are adaptions of film or TV properties. The M.O. of these sourpusses is to take the immense popularity of a brand among young people and use it as a cudgel with which to beat its theatrical adaptation.

To me, these hoary hand-wringings are a cumulative canard bigger than the worldwide branding of Donald Duck (you knew I’d get to Disney eventually). They betray a lack of perspective for Broadway history and, most disconcerting to me, a bias against children and their predilections. More kids than ever are attending Broadway musicals — they (well, their parents) are paying the same money for their bill of fare; shouldn’t they be given an opportunity to glance over the menu? To paraphrase a family-friendly musical from 1960, “Bye Bye Birdie,” what’s the matter with shows for kids today?

First, however, the idea that Broadway has only recently awakened to the commercial potential of a brand or source material previously endorsed by popular culture is absurd. George Bernard Shaw’s “Pygmalion” was first produced over a century ago; it had already been revived on Broadway several times and made into an Academy Award-winning film when Lerner and Loewe began hawking their musical adaptation around town in the early 1950s. CBS decided to underwrite the entire investment of “My Fair Lady,” in large part because if a stage musical didn’t pan out, the network would have been happy to broadcast a prime-time TV version of “Pygmalion” starring Rex Harrison instead; Shaw’s reputation as a “brand” had already preceded itself.