The AO is always a tough one to judge.
Analyzing only from the Open Era (1968) onward I look at it this way,
Women's game, the AO didn't become a full fledged "have to go there , equal to the other Majors" until about 1981-82 when Chrissie and Martina started going there year in and year out and all the other women followed. By the time of Steffi Graff her whole career she traveled down to OZ as did all the top WTA. To put it in perspective , both Martina and Chrissie have said that in hindsight, if they had know the Majors would all count so much afterward in their legacy, they would have gone to the AO more.
Now most of the top men started going to the AO on a regular basis around 1983 onward, that year Lendl, Wilander, Edberg, Johnny Mac, all went down and the next year the young Boris Becker started the annual trek. There were the odd man out, like Agassi, who inexplicably skipped the AO until 1995, and ironically that became his most successful Major as far as wins.
Going forward , the whole generation around the Sampras era, starting with Pete in 1989, all that group of ATP players it became almost mandatory to go to the AO, so 89-92 when those newcomers (Courier, Chang, Stich, Goran, Korda, Bruguera, Kraijeck,
Costa, etc) came of age they knew nothing but going to 4 Majors regularly.
So I would opine that in the last 30+ years the AO is equal in importance as the other Majors.
Now the French Open is another matter, except for the WTT days circa 1975-1978, most of the top players have played that tournament throughout the Open Era. It was the bete noire of such players as Pete Sampras, Edberg, Becker, Connors (only played it sporadically) and especially Johnny Mac who wanted to win it badly and came tantalizingly close in 1984. My fave Edberg also came sooo close to winning it after leading Chang but ultimately losing in 5 excruciating sets back in 1989. Even the serve and volley Aussies of the 60's and 70's made the trek to Paris to battle the red clay. Rod Laver won it in his Grand Slam year in 1969 and he was hardly a dirtballer.