SF64 holds up just fine. The 3DS version wasn't a technical showpiece at all, being a port of a game that was almost 20 years old, and yet it holds the second highest Metacritic score among all games with Star Fox in the title (with the first being the very game its a port of) and according to the site we're on, has sold almost a million carts when it launched at a time well before the 3DS found its footing. Had it not been woefully underprinted (prices for physical copies online shot up very quickly as proof) or if it became a Nintendo Selects game, that number would be higher. I fail to see what makes the game so "simple as far as gameplay goes" that works against it. Is it because you fly forward and shoot things with lasers? Mario platformers are simple because you run, jump and collect stars. FPSes are simple because you're a floating gun that goes around and shoots things. Your very statement that Star Fox hasn't aged well because of the lack of cutting edge graphics goes against your point when SF643D scored well critically and outperformed Nintendo's expectations commercially.
And yes, no Star Fox game has ever had success without it being a display of cutting edge technology, because no Star Fox game has deserved success outside of the two that just happened to be displays of cutting edge technology. Every single SF game after SF64 and outside of the DS entry has been on Nintendo's worst selling console at the time or on a console that was badly struggling at the time. Also, every single SF game after SF64 has either been whored out to an outside studio that had nothing to do with the first two games (the ones people love), drastically altered the gameplay in ways that made them Star Fox games in name only, had unwanted, gimmicky gameplay shoehorned in (to show off the consoles technology!), or been remakes.
- Star Fox Adventures (GameCube, 2002) - Wasn't even supposed to be an SF game in the first place, developed by Rare after most of the talent left, Fox and crew shoehorned in by Miyamoto, Fox spent 99 percent of the time on foot, second-rate Zelda clone. Not a rail shooter. Also, GameCube.
- Star Fox Assault (GameCube, 2005) - Developed by Namco, closest thing to a rail shooter (about 60 percent of the time) before SF0, but bad shooting mechanics, on-foot controls, mission designs and an extremely short and easy story mode turned lot of people off. Also, the GameCube was deader than disco at this point.
- Star Fox Command (Q-Games, 2006) - Developed by Q-Games, some folks who had been part of the original Star Fox development team, but still went too far away from the gameplay of the first two games for most people's tastes. Sold a respectable half a million units.
- Star Fox Zero (Platinum Games, 2016) - Developed by Platinum Games, almost a return to form but good old Miyamoto forced unwanted Gamepad controls onto players, forcing them to use an undesirable control scheme and camera system that many critics and players panned. Also showed its roots as a Wii project in some areas. Also, released late in the Wii U's lifecycle, a console deader than GameCube.
So basically, we don't yet have an example of a Star Fox game that is a rail shooter that flopped. And like I said, Command is the only Star Fox game that wasn't sent out to die on a console that no one owned. You can tell me that Star Fox doesn't work outside of being a technical showpiece after I get my non-fucked up Star Fox game with GOOD controls and WANTED gameplay on a SUCCESSFUL CONSOLE that the masses actually own, and that game bombs. Until then, blame it on Nintendo for constantly whoring out the game to different studios with drastically different gameplay from game-to-game and sending them out to die on consoles that most people have never actually seen in real life.
Also, how is the Switch version of Starlink doing compared to the others saleswise?