That's quite literally the point. Is pretty bad when one of your most recent examples of a big new IP is 20 years old.
Labo isn't really made by one of Nintendo's bigger teams, that is their experiment team iirc. I agree with Arms but like, it sold well and if we're being honest one of the bigger problems with it is that it covered a niche Nintendo already had down.
I'm also curious, if what you say is true, then what franchise was sacrificed for the sake of Splatoon?
Nintendo cant even give many of their current IPs the time of day, so whats the point of adding to the pile? I don't know what franchises didn't happen because of Splatoon, but I do know that that franchise will now be made way before any other franchise that doesn't already sell millions.
But that was already the case, which is why this is a terrible, terrible argument.
F-Zero, Kid Icarus, Punch-Out!!, Earthbound, StarTropics, Wario Land are the ones you listed. F-Zero hasn't been made since like 2003 and and even then it was a third party title. Punch-Out!! hasn't been made since 2009 and was again developed by a third party. Mother hasn't been touched since forever and the creator doesn't even want to make a new one. StarTropics hasn't been touched in forever and unless they just straight up rebooted the series, the demand would be minimal at best (most people don't even know what it is, or what it represents even). And again Wario Land was developed by a third party developer, almost 12 years ago. To be clear, I'm specifying third party because I'm talking about Nintendo's main teams takling new IP. As I already stated, I think third parties are doing a pretty good job of making a decent amount of new IP, what I'm really interested in is a team as legendary as the Mario team making a completely original project, not whether Good Feel or Next Level make another Punch-Out or Wario Land. I'm fine if they do. Though honestly, is WarioLand, another 2D platformer in an era where Nintendo is housing 4/5 concurrent 2D platformer series, really as important as a new IP that covers new niches?
Now, ok, maybe you could make an argument that the demand for new games becomes fulfilled by new IP, and this lack of leftover demand would make Nintendo not care enough to go into their back catalog and create new entries in once beloved series. This is a fair argument, and I actually think it's one that's very underrated in regards to, for example, ports and remakes. A lot of titles that Nintendo probably would have had to make for the Switch one way or another (whether it be outsourcing or developing in-house) had porting literally been impossible, are now not needed because Nintendo can just port over older games. A new 2D Donkey Kong really isn't needed, for example, when you have a port which satisfies the market. A brand new 2D Zelda isn't needed when, for example, you have Link's Awakening Remake. However, this is a good argument for games that had a chance to be made. In reality, the demand for all the games you listed has been dried for a long, long, long time, with the exception of Kid Icarus but it's a miracle Uprising was created in the first place.
It's ironic, because you say that Nintendo can't give their "current" IPs the time of day, when none of those are current. I'm not going to pretend like the Wii is this ancient mystical temple that hasn't been visited in a thousand years but, it's pretty old, and those games really aren't current or relevant right now.
Lastly, I think a lot of the same people who argue that Nintendo should make more new IP, are also the same people who argue Nintendo should hire more staff, and that Nintendo should use their backlog IP more. So I don't even really disagree with your premise. I just take that as an example of why Nintendo should expand, whether it be through more partnerships or internally.