They change qualifying every few years because the previous qualifying gimmick has worn out. Or something.
Now they are changing qualifying a month before the first race, and AFTER teams have already been forced to select tires for the first race weekend from the range of compounds (speaking of gimmicks...).
Perhaps the next qualifying fad will be to change the qualifying rules after the qualifying session has already begun. The F1 Strategy Group and F1 Commission will be quarantined in the FIA motor home just before qualy begins. They'll be required to vote on random changes at 5 minute intervals. If 4 consecutive new proposals fail to pass, then the rules will automatically revert to one of the previous qualifying formats which will be randomly selected by Jean Todt spinning a giant roulette wheel. The roulette wheel result can of course be nullified by Bernie giving a negative press conference during the qualifying session.

