We already know what's out there, we have telescopes and probes. We're not going to find jungles on Venus or something like that. We're not going to meet the Vulcans.
> We already know what's out there, we have telescopes and probes.
The entire field of astrobiology is a big giant question mark despite our telescopes and probes. If we'd have sent humans to Mars instead of probes, we'd either have proof of past or present life, or we'd have very convincing evidence that it doesn't or never did exist. And we'd have had that relatively quickly. Here, decades later, we know a lot more, but we don't have this one basic fact.
We are still uncovering where and how life is in Antarctica, and we’ve had humans there for decades. What makes you so sure we would be so much quicker to figure out things on Mars?
Studying Antarctica is different; we already know life is there, so we're studying the minutiae of "where and how". On Mars, we're yet to answer the two most critical questions: whether there is - or was - life, and if so, how it is related to the life on Earth, if at all.
As for figuring this out quicker: an astronaut would be able to leave their ship/base, go find some interesting rock, bag it, bring it back, slice it and observe under microscope, all in time it would take the rover to just drive towards the nearest rock. All it takes for a human to be a better sample collector than most advanced of robots on Earth is a shovel.
Robotic missions scale better and may still be more cost-effective, if we built and sent a crewed science ship to Mars orbit. It doesn't have to land, the crew could pilot dozens of rovers remotely at the same time - but this way, with much higher bandwidth (could actually drive FPV looking through a HD camera) and much less lag (which, for Earth-Mars link, is 3 to 22 minutes, depending on relative position of the planets, and that's one way, not RTT). I'd say this is the perfect trade-off until we make more progress on AI front, but it requires manned flights. And if we'll be at the point of sending science ships to Mars, we won't be that far from landing humans there anyway.
"Let's see what's out there!"
It's human nature.