It remains to be seen whether they are just paying less rent, or there are other disadvantages. Beside the obvious maintenance issue (will landlords invest more than legally mandated?), a german-specific issue is that it is quite common in Germany that renters who want to end their lease search for their own successors. The reason is that apartments often come without kitchens, low-end apartments even without flooring. The renter needs to take care of that, and if you end your lease, your investment is lost. Unless you find a successor who is willing to pay for it, which is quite easy if you live in a desired, low-rent apartment. Where I live (outside Berlin), people pay several thousand euros "for kitchen and floors" to the previous tenant to get a city-owned, low-rent apartment. Often they pay more than the kitchen and floors are actually worth, even though legally they are not even required to pay for this. But it's the price to be chosen as successor among many applicants. Landlords usually play along, as it's less work for them and this process will ensure that they get only the most affluent renters. I expect that renters in Berlin will be willing to pay even more to get one of the regulated apartments, as they are even cheaper.