Personal opinion, based on the experience I've had across some games I've played lately:
People talk about DBFZ netcode being lackluster, which somehow is, but the game has more things mechanically going on to register and I've had far more enjoying matches in that netcode than on MK11 (while MK11 has more graphics to load up and interactions, etc). Some also tend to say that on PC at 1 or 2 frames of input lag it feels like offline PS4, while MK11 is still locked in 3.
Even at a delay based netcode, DBFZ can really show its colors when played at low delay. MK11 feels wonky somehow compared to it when both are played at optimal settings. Meanwhile in DBFZ, anything from up 5 frames make it feel atrocious, and don't even make me talk when it becomes variable. However, say what you want, its not bad when its played optimally.
To me, MK11 feels nothing like rollback, It has the input delay feel since the rollback goes unnoticed (which is cool, I guess, I've only noticed it when getting hit by a fatal from a characters back, lol). KI, for example, has a more dynamic rollback making it warp a lot more in its rollback than MK11. Its just different, it doesnt make any of these two worse than the other in any way. An outcome (eg. oki, crossup caught by mashing) may play different in a match and thats it. Yet, MK11 can handle it better overall when playing against players from afar, its not bad. In addition, it has crossplay. It seems they aimed for a smooth experience across players distance, and it does a pretty good job at it.
Sometimes it appears to me that MKX netcode was better than MK11 too. Maybe it has to do with the graphical quality improvement from one to another, with a lot of scenery animations to boot up, ect.
With these many things NRS actually achieved a pretty nice balanced netcode to bring their vision of game design to a online setting, since its possible to handle a beautiful and heavy game. If thats the case, they should get rid of some of these mechanics and unecessary graphical things (lots of scenery animations going on) from their engine in their future games so they can run more smoothly online.
There isn't much more to improve as of now, besides online ecosystem changes, because it could result in a disastrous experience, so we just have to accept it as it is.