Sporty models and convertibles are niche segments that sell in low volumes, minuscule in relative terms, and while great image builders, require a commitment that OEMs are reluctant to make, given the return on those investments.
Their sales curves typically peak early in the model cycle, and decline as they get older, which doesn't encourage further investment, so whatever refreshes and facelifts those models receive are typically more modest and less frequent. Which also hurts those models because they are more perishable, and rely more on being current, and fashionable. Nobody has to buy a Camaro. They do have to buy the SUV or minivan to haul stuff, or their family around.
If selling lower volumes of high-trim models, vs. higher volumes of low-trim (in spec, and margin) plus high-trim models can make the same amount of money, the former still works out more favorably, because it doesn't require the same investment in production costs, carries less risk, and frees up capacity on the lines to make other more profitable, if mundane models, in higher volumes.
Airlines haven't turned their focus to investments in improving the experience for first- and business-class passengers, while making steerage economy more miserable, by mistake.
Demand for the pricey cabin seats is less elastic, and more profitable. And since people are still willing to accept junk fees, in exchange for the deception of lower base fares, they can do alright on the cheap cabins as well, as long as they keep them loaded with passengers. Which is what the recent trends show.