Commercials of any length, especially those that employ celebrities or the like, are expensive. You're not talking a couple of people with a GoPro, but the hiring of a full-on professional production company. The cost is prohibitive for most airlines during the good times, nevermind when they're losing millions of dollars a day. Plus, from the time a commercial is planned, shot, edited, reviewed, and published, the guidance from the government has changed, voiding the message. Even if you get the commercial out with the same governmental message, it is now on the company to edit that commercial with every mood swing. Just to add fuel to the fire, the message on a BA or Virgin flight departing Heathrow would not be the same message as the return flight. You'd have to shoot a variation for each country that you operate into. Heck, even different provinces and states within those countries have different messages, so you'd have to have a specific message covering the requirements of New York versus California, Ontario versus British Columbia, England versus Australia.
Until the governments of the world can come to a central and consistent message on the issue, there is no sense for any company to put their dwindling resources into something that won't be valid by the time the first meeting is over with.