Another article on why solar system habitability zones don't necessarily equate to a habitable planet (and likewise)

The Earth and the Moon compared to Io. A 'superIo' larger than the Earth could be warm enough to support life even outside the habitability zone.

Here's another article on how a planet's tides can play a large role in whether a planet is habitable or not, giving the possibility that planets within a habitable zone are actually too hot for life but that those out of the zone won't necessarily be frozen balls of snow either. This tidal heating is over the billions of years as well, giving lots of time for life to develop and thrive.

After all, without the Gulf Stream Western Europe would be as cold as Russia. Here's what the article says:

New research by Brian Jackson, Rory Barnes and Richard Greenberg of UA's Lunar and Planetary Laboratory shows that tides can play a major role in heating terrestrial planets, creating hellish conditions on rocky alien worlds that otherwise might be livable. And just the other way, tidal heat can also create conditions favorable to life on planets that would otherwise be unlivable.

and:

If the recently discovered "super-Earths" -- extrasolar planets only 2-to-10 times as massive as Earth -- are indeed terrestrial, tidal heating may be great enough to melt them, or at least produce volcanism on par with Jupiter's moon, Io, "dimming their prospects for habitability," Jackson said. So some of the recently discovered super-Earths may be more like "super-Ios," he said. The lo moon is the most volcanically active body in our solar system.

"Tidal heating scales with planet mass, so we expect that most easily detectable super-Earths will be dominated by volcanic activity," Jackson said. "That's one of our first conclusions from this work, that the first Earth-like planets found are probably going to be strongly heated and have big volcanoes. Even if Earth-like planets are found within the habitable zone, they may not be habitable because they will be overwhelmed by this tidal heating."