A week after Warner Bros.’ bombshell announcement that it will debut its 2021 film slate on HBO Max and theaters on the same day, the backlash from filmmakers, producers, agents and guilds is rising to a deafening din. And the theater owners aren’t too happy either. Filmmakers Judd Apatow, Christopher Nolan, Denis Villeneuve — the latter two among the studio’s biggest creators of the last few years — all spoke out publicly this week against Warner Bros.’ decision, with Apatow calling it “disrespectful” and Villeneuve calling it a “hijacking.” Major producers who work with the studio seemed shocked into silence, though Legendary let it be known that it was exploring a lawsuit over the aborted releases of upcoming “Godzilla vs. Kong” and “Dune,” two Warner films that it financed. Meanwhile, the Directors Guild of America and CAA and WME — often on opposing sides of business issues — both sent scathing letters to the studio to protest what they regarded as a brutally abrupt move by Warner’s corporate leadership led by CEO Jason Kilar. “The blind-side Warner Brothers announcement Thursday was entirely unacceptable to CAA and to the clients we represent,” CAA President Richard Lovett wrote in a letter that...