What do housing upgrades accomplish?

I know there are questions about how to upgrade your housing efficiently(see: How can you make more money and upgrade flats), but I'm more curious as to why someone would bother. Seems to me that it just costs more, with no direct benefit.

So, what are the advantages/disadvantages of upgrading your housing?

The only real purpose of upgrading your apartment is to achieve the "Worker's Best" hidden achievement for moving into a class-5 apartment. Note that the prices quoted are the new rates, not the increases, so the class-7 is just more expensive rent, but the heating costs the same as the class-8:

• Class-7 (rent=30, heating=10)
• Class-6 (rent=50, heating=5)
• Class-5 (rent=?, heating=?)

Each upgrade will set you back 100 credits per class, and if for some reason you feel the need to downgrade, you can occasionally do this as well, for which you gain 75 credits per class.

At first, it seems like there is no real benefit.

However; if you took the EZIC gift of 1000 credits on day 11, then upgrading to a class 7 apartment will result in a small win on day 14, when all your money is confiscated.

On the same day, you are also given the option to downgrade your apartment, which gives you 75 credits.