That's what I'm asking myself: why is the space station so unpopular among space afficionados?

Because it seems so expensive (while it's nothing compared to all other social programs)?

Because astronauts are not going anywhere?
But they ARE in space, in low earth orbit!! They went there!
The argument about the Moon and Mars being destinations while the space station is not, is wrong! The space station is a destination and the Moon and Mars will also become boring even to the space afficionados.
It all depends on what they're doing.

We have to ask ourselves: am I honest when I'm saying the space station is not worth it, while Mars is ?
For one thing, humans on Mars is so far in the future I know I won't live, so I would rather support something that produced results in the short term.
Mars has a lot of support because no one has ever been there.
Once that's done, it will follow the path of the Apollo program.
To avoid that, the supporters already claim Mars is an objective because we'll colonize it!
I'm sure they're not honest with themselves. To colonize a world is very different from exploring it. To colonize is to (almost) live like on Earth, but on Mars.
To explore is exciting but as long as the exploration lasts and then they come back. Exploration is an intense but short lived experience and that is why many want Mars: to satisfy our curiosity.
We're not yet in the manned Mars exploration phase, which is the most exciting part of going to Mars, but we don't want to stop once it's done , so we need to bring up the colonization reason. It's far too early, I'm afraid.
Here we are: not wanting humans in low earth orbit, but most surely on Mars. There's a flaw somewhere in that wish. It takes too long and one day, the same about Mars will be felt as about the space station today.