Reason #3: Many pro wrestling fans have literally grown up hearing him call matches.
When you're in an industry as long as Jim Ross has been in sports entertainment, you're going to have lifelong fans--literally.
Many wrestling fans were children when Jim Ross began his announce career, and they grew up hearing him call matches. Then they became adults, had children and careers, and through it all the one constant of their world was Jim Ross calling pro wrestling matches. Now those same fans have created multi generational fanbases for Jim Ross, as their children are fans of his as well.
If there's one thing that audiences crave, it's a certain degree of familiarity--why else would Supernatural run for seventeen seasons? Jim Ross provides that familiarity with his famous voice and no nonsense delivery on the announce desk, and that's just one more reason why him signing with AEW is a huge deal.