It's interesting that this is coming up based on a name change, when the rules for the Ark Module are exactly the same as the Orbital Habitat, and they have been around for many years.
Besides the other points raised in response, I would note that "well AcKsHuLlY..." the matter was raised due to the potential for an enemy to board an Ark Module and capture the population onboard, which has not previously been the case - if an enemy captured an old OrbHab the population would remain grounded and just die off from a lack of 'infrastructure'. The question was whether those 200,000 or so people might not put up a little bit more of a fight when faced with the possibility of forced relocation to an alien gallicite mine. After this we have had the additional comments from the Realism Brigade™ about crew requirement to operate the facility.
Technically this also applies to the luxury passenger module, but no one actually uses that for transporting colonists so it hasn't really come up before.
IMO though I felt that orbital habitats were too cheap/easy to put into place before. If you ask me I think it should be more expensive than infrastructure to use orbital habitats/arks for example for the Jovian Moons ( with colony costs of around 6-8 ) but cheaper for Venus.
I think it is a good balance point where it is. Currently,
OrbHabs match the efficiency of regular infrastructure for a colony cost between 5.0 and 6.0, and there's good reasons to consider both options for a range of CCs on either side of that breakpoint. For example, for colonizing Jovian moons OrbHabs/Arks may be nominally cheaper but would require a tug to get into place while infrastructure can be shifted by a robust civilian shipping sector for just a few spacebucks.
This is similar to how the changes to Ark Modules make them cost-effective modes of colonist transport but in practice not always easy to use due to large size, so that more expensive colony ships will likely remain the most time-efficient mode of transport for at least a good portion of the game. In the late game this may change but that is fine as a big part of the tech tree design in Aurora is how different technologies come into their own at different times during the game.