Except it pretty much is all there is to it. If F-Zero was selling even half a million reliably they'd still be making them. It always comes back to sales as the #1 thing. After that point it gets a little muddy.
That's not all there is to it because games like Wave Race Blue Storm did NOT sell poorly! Nintendo hasn't even tried releasing a Wave Race game in 13 years. You cannot say that this is because they don't sell. As for 1080, I don't know how Avalanche sold, but I think it did okay, though not as well as Blue Storm. And F-Zero GX did okay as well; not great, but not terribly either. 300,000 on the Gamecube's not bad, and maybe the series could have done better on the Wii, but Nintendo never tried.
Check the sales of the GBA F-Zero games. Sales were going down the toilet.
The GBA F-Zero games weren't any good! I love F-Zero too and didn't buy any of them new, and that was the right decision. I don't know why Nintendo kept making those mediocre GBA F-Zeros, but all it did was hurt the franchise with their lacking quality. That's nothing that another great console game couldn't fix, though!
They figured it's a niche series (it is) that isn't going to attract people to buy the hardware. It also doesn't have "general" appeal. Captain Falcon isn't a mascot character like Donkey Kong and Kirby. Wave Race guy isn't a bankable character. Excitebike guy isn't a bankable character. Notice that DK and Kirby have value outside of their games, in merchandising.
I don't buy this argument. Nintendo doesn't only make games with hugely marketable stars -- how about the new Codename Steam game for the 3DS? That's clearly not a game with the biggest stars, and I doubt it'll be a huge hit either. It could be successful, but a big hit? We'll see I guess. But regardless, it's being made, while no non-kart racing games are. None! Also, of course, Wave Race and Excitebike are both franchises about the gameplay over any specific graphical look. Excitebike has had several, between the motorcycle games, Excite Truck, and Excitebots. Wave Race has had both boats (GB) and jetskis. If you want "marketable stars" then invent some and try to sell it, though it's kind of pointless in that kind of game. That's fine though, those franchises did well based on their gameplay. And as for F-Zero, Captain Falcon keeps appearing in Smash Bros. games -- Nintendo clearly thinks that he's at least somewhat marketable!
I love F-Zero, and I think there's a decent chance we get a new one now that we're in the HD era (or a HD remake of GX or something), but it's easy to see why they haven't made one since the GBA games cratered.
No, I don't think there is. If you're using mediocre to bad games as your test for whether a series is worth continuing of course you're going to get a negative result! And anyway, saying "every single racing game that isn't Mario Kart all failed to sell" isn't true... some did, others didn't.