Steph's appeared even less than all of them and She's a RobinIt took forever for Nightwing to get any proper other media appearances though. He was lagging way behind for decades, and now that he is finally getting them his appearances as Robin are lessening. They are more likely to use Damian, Tim, or even Jason now who has seen an uptick in his appearances as Robin. That will increase even more as time goes on as Dick moves further and further away from the Robin identity, imo.
But I think we will just have to agree to disagree on this. I don't see how Nightwing is better than if Dick didn't just retain the Robin identity, especially with how easily DC strips Dick of that history that was vital to his character and how the Nightwing identity had to be saved by the Batman office anyway. People aren't even sure what Nightwing's origin story is right now. It's ridiculous while Robin's is cemented in popular culture. There is just no comparison between the two identities to me. I mean those post crisis NTT stories that were SO important are basically irrelevant now. Most of the classic and memorable NTT stories happened when Dick was Robin anyway. So Dick losing one of the few iconic identities in comics for stories that DC basically doesn't care about anymore will always be a negative outcome in my opinion.
You aren't taking their stores and just saying that is what would have been done with Dick, but it is more about consolidating their opportunities. So Dick might have been written by more of the late 80s Batman writers that redefined the franchise, Dick would have gotten a solo book sooner, would have been the one to get a modern Robin costume, he might have been part of the Young Justice team that they wanted to create and so on. They might have even done a Death in the Family style story with Dick, but this time Robin survives it. JGL's character in The Dark Knight Returns movie by Nolan probably would have just been Dick Grayson instead of "Robin". Things like that where all of the Robin's opportunities are aligned within one single character.