Completely anecdotal: perhaps a large concentration of these flats are in East Germany, where the population tends to be older, the Soviet Union was known to build a large quantity of housing, perhaps there could be a confluence of modern tastes and as the article pointed out, little around to do, that cause people not to seek these properties out.
Nay, that would be "Plattenbau", meaning built(ge(bau)t) out of prefabbed concrete slabs(platte) and steel bars. Which btw. isn't that limited to former eastern Germany.
The thing is, these were often badly insulated against sounds from the neighbors, also the neighbors often weren't particularly desirable, because badly educated and in general stupid people tend to agglomerate there. Because it is 'social' housing, mostly. Little around to do depends on what you'd want to do? Since they are often on the outskirts, you're faster in the nature, and maybe even better air in general, because the stink/smog of downtown isn't so intense there. If you'd like to take a bath in the unwashed masses, doing speciality shopping, dining, there is public transportation 24/7 with service at least every 20 minutes during the night, and 5 to 10 during the day. Taking you downtown in 20 minutes tops.
At least where I still own a condo which I rarely visit anymore.
