though unable to answer explicitly a hypothetical of a hypothetical of a fiction.. it is a fun, and arguably healthy'productive exercise to dream on it..
from the perspective of the film makers it seemed like a shout out to the colony art nasa published a while back(i), similar to the shout out to event horizon: 'your explanation opened my mind, bending space time like a piece of paper and passing through it like a pencil.. i'll take it to the next level, what is a hole in three dimensions? open the paper and look at the hole as a circle forming a sphere' fun stuff
if we want to examine the practicality of a cylindrical colony i think we could come up with something.. maybe as a safety measure from space debris? maybe as an engineering consideration: it was easier to build an accommodatingly sized colony like this? easier to maintain a controlled climate? maybe as a lighting'photosynthesis consideration?
perhaps it's a 'so preoccupied with whether they could' punchline? perhaps the other side of the column is also utilised space: imagine almost doubling the surface area of the planet by colonising both the surface and the interior of the planet with an inverted zenith; and the film only showed us inside the column, again, as a wink at the audience
(i) http://settlement.arc.nasa.gov/70sArt/art.html