It isn't easy to study Venus. The hot acid atmosphere dissolves space probes. Only one probe's temperature gauges survived all the way to the surface, and even that probe didn't last long. The article says that the pressure, temperature, and composition of the Venusian atmosphere could make it a supercritical fluid, acting like both a gas and a liquid. I don't know if it could act like either alternately, though that would be cool. Did anybody else read Close to Critical?
A terrestrial measurement at much lower temperatures suggests that the gases in the atmosphere might separate out under those conditions, leaving more of the dense CO2 at the bottom, even if the bottom level is at higher temperature. (The calculation of what sort of temperature distribution Venus should have is hard, and I won't attempt it.) Extrapolating to conditions on Venus is . . . um . . . speculative. As the article says, they've two choices: try another Venus probe or try to reproduce Venus conditions in the lab. The lab is probably cheaper.
Why would this be important enough to sort out? The paper notes that there would be much less nitrogen in the atmosphere of Venus if it were excluded from the lowest, most dense layer. And that could influence how we understand both the formation and evolution of the planet. It could also inform our understanding of a variety of other planets, where gases exist under similarly extreme conditions.
That's the sort of stuff that goes in the grant proposal. What's the real reason for trying to study it? It's weird and cool.
Plus, let's face it—it would be pretty cool to have something so bizarre happening on a planet that could be Earth's twin if it were elsewhere in the Solar System.
Yes, I know it is odd to think of Venus' atmosphere as "cool."