The ultra fuel efficient cars of the 90's had lean burn mode. As good as it was for sipping fuel, it had its drawbacks.
Back then, the switch between stoichiometric and lean burn was a noticeable stumble, and once in lean burn the throttle response was pretty inexistant and power output in regards to throttle position varied drastically between modes. Thus there were driveability drawbacks which meant it could never be a truly mainstream product. Most drivers also either didn't know or didn't care enough to drive in a way that maximized the use of lean burn, so fuel economy gains weren't as impressive as they should of been.
Then there's NOX emissions. Lean-burn motors used less fuel but emitted much more NOX than a traditional engine. It wasn't a problem for manufacturers in the early 90's, but as emission régulations tightened, more and more pressure was felt by manufacturers producing these motors. And you can see the result in the first generation Honda Insight. It had a lean burn motor, and two cats. One was a standard three way cat, and the other was solely for burning excess NOX and unburnt HC. It worked great, the Insight was classified as a ULEV vehicle, but the second cat alone retailed for 1200$, which meant that anyone with a ''cheap'' car like the VX would probably have chopped it off when it went bad instead of buying a new one. So lean-burn moved upmarket, into the Insight, which despite it's frugality, was no longer a bare bones offering like the VX, but a slighlty upmarket offering with an elaborate drivetrain which was aimed at silicon valley types.
So there you have it, emissions and cost killed the ultra lean burn fuel injected motor.
But the upside is that cars today are just as efficient and have less drawbacks in terms of driveability, produce less emissions, are safer and have more Equipment. Direct injection and modern ECU's can run leaner modes and the transition is not noticeable like it was 20 years ago.
So I wouldn't go as far as saying that ''on se fait niaiser a quelque part''.