What is the point in heat?

[TNTwaffle]

You see that little thing telling you the temperature next to your O2? What does that have to do with anything, it seems synced with the O2 for some reason as well. Is it for your ship or for you? Can freezing temperatures kill you? Or is it like something for your cores?

[Pyrrhus]

Heat conserve energy of player's spacesuit which cuts down numerous of trips to medical station for recharging.

[Wygos]

Energy consumption.
If you overheat or too cold your suit eats more energy. Nothing more.

[Buzzard]

Temperature is a separate mechanic from O2. If you go up to the frozen poles of Earth-like, you can be freezing in a high O2 environment.
Cold, then freezing use more suit power to keep you warm. Hot, then Inferno use more power to keep you from being baked. All temps other than Warm will start damaging you when the suit runs out of power completely. The more extreme the temp, the faster the suit and health drain.

The reason you were seeing temp and O2 levels dropping together is due to the thinning of the atmosphere.

[Ryukki]

Its a shame how this "new" mechanic is so empty. Its just the same effect of having no o2, you'll end up asking "Why am I dying!?" only to realize your "freezing" to death. I stood in a arctic pole and I never got cold only when it got to night on a planet.
For me this feature is bare bone and hopefully they will work on it.
https://support.keenswh.com/spaceengineers/general/topic/make-the-new-temperature-mechanic-have-visual-effects_1