I'm kind of OK with athletes opting out from media coverage, as long as they're consistent about it. Meaning, if you're saying anxiety means you don't want to be interviewed before big matches, it also means you don't do interviews after big wins. However, I kind of doubt most athletes would be consistent with this. In particular, I'm thinking of Kevin Durant, who was happy to do four relatively friendly, softball podcasts with Bill Simmons, but not much other stuff.
When it comes to the idea that the interviews and access are helping to "grow the game" though, I kind of think that effect is minimal or non-existent. The most popular sports league in the U.S. is the NFL, and most of those players give forking awful interviews. Lacrosse and hockey feature interviews with players and coaches *during the game* and I've never heard that cited as a reason why people like either sport. Ultimately, it's the product on the field that puts butts in seats. If Osaka is going to play better and be a more compelling athletic force on the court with no media interviews, then it's probably in that sport's best interest if she doesn't.