So I watched Synthetic Man's review of Kirby Air Riders and he makes a point about multiplayer games that don't get updated in that they get boring once someone knows the ins and outs of the game.
He points out how he was able to memorize all the spawn points in City Trial and how his brother won't play with him anymore because of it. I had the exact same experience when I played 007 Nightfire with my brother, many years ago. We memorized all the grappling hook locations on all the maps and there was no limit on the distance you can grapple to. So we were just zip-lining across the map and we couldn't kill each other because we were quick to hookshot to the other side. That's why it's hard for me to get into multiplayer games, it's quick enough for me to find every exploit.
@xianc78 at a casual level this happens for sure, but it's not really a problem at higher levels of play. That's the nice thing about online multiplayer. It's also good the game has a ranking system because that means Sakurai developed the game with higher levels of play in mind. It also has way more content and chaos than the original, so I don't think that issue will pop up as fast unless you were just doing 1v1s or something.
Look at fighting games. Those only ever get updates with characters, and for the most part the more popular fighting games are the ones that haven't been updated in a very long time. Just because the gameplay doesn't change doesn't mean that the meta won't. Hell look at something like Tetris lol.
Of course that is only talking about higher levels of play and I've run into the same exact issue playing pretty much any versus mode game with friends irl. I get really good at it then they don't want to play with me anymore. So if you don't have access to those higher play levels to keep things challenging and find people to play with, I can understand how that would be frustrating.