How does that make it useless or stupid? It's perfectly useful and entirely valid if you're interested in planets that can sustain life.
No, it's not, if Titan ranks as 70% as habitable as Earth
You, however, seem only interested in planets that can sustain a "flourishing biosphere" -- which is even more stupid and useless.
No, that's what most people understand under
habitable. I don't give a damn if some ball of ice can possibly sustain conditions that could allow some primitive single-cell lifeforms to arise, linger for a while, and then die out having evolved into nothing else.
There are clearly no planets or bodies in the solar system that are capable of sustaining a flourishing biosphere. That is demonstrably true - just look at the other planets. And finding evidence that a planet in some other solar system is capable of sustaining human life is basically impossible with current technology.
Which is why it is pointless to make "planetary habitability charts" at this point and take them seriously. In our Solar system, there are just a few places where we suspect some form of life might exist, and we don't know enough about any of the extrasolar planets to even assume anything.
A body that's capable of sustaining single-cell life, however, is well within the realms of possibility. And finding evidence to suggest that a planet is capable of sustaining this broader form of life is much, much easier. You might not find single-cell life particularly interesting, and you might only find studies useful or interesting if they find evidence for the existence of capable of sustaining human-like alien life, but science doesn't exist to satisfy your narrow interests.
Blah blah blah. I am sorry, but if you take seriously an index that's claiming that Gliese 581d is 0.05 points more habitable than Gliese 581c, than it's pointless to even debate this with you - it's obviously absurd.
"I think Zeus is 10 cm taller than Thor, prove me wrong!"
It's still a bit puzzling that we didn't discover any sign of a civilization that's a couple of hundred thousand years beyond us.
I like to think we're just one fo the first intelligent species in this galaxy, but that's only likely if there's not that much life around.
Why? There could have been thousands of them, each having evolved in a very short (from astronomical perspective) timespan of several tens of thousands of years, and then moved beyond. There is no reason to assume they're extinct.
Our Galaxy is what, 10 billion years old? Our Solar System is only about 5 billion years old. I think the chance that we're the very first intelligent lifeform to evolve here isn't very high.
