perhaps you're missing the point a little...
for a start, practically nobody in any college will be rendering a very long scene like that. and there is a chance that if they are, then they'll be able to reserve a computer in a lab.
Yes, the college could spend all it's money making a single task rendering farm, but, they'll have spent more than they spent on the work stations putting a large server farm in, (and it'd cost more in hosting). -even when a college hosts it's own servers it's still billed internally, because colleges rent out their server room space and connection to other businesses too, (at least the university that I used to work at did).
anyway, if they'd have spent all the money and more that they spent on the work stations on a single purpose rendering farm, then they'd have a beast of a farm, that saw very little use, took up hosting space, incurred yearly costs, and they'd still have no workstations.
so they've gone down the most practical route of buying decent workstations so that all students at the college can benefit.
remember it's not just the rendering programs that will be being used, there are probably other students doing design work, desktop publishing etc. and the students that just need word are still going to be happy too!