These were highly desirable at the time. Most people lived in old houses with a bathroom in the staircase or even outside, coal fired oven heating in some rooms, ancient windows, bathtub in the kitchen, etc. The government wasn’t investing in renovation or improvements of old buildings, so they kept falling apart.
The new Plattenbauten (commie blocks) had central heating, warm water, modern windows, modern bathrooms, shopping, healthcare, and schools nearby, parking spots, public transport connections, etc.
People would marry and have kids early to be eligible to be assigned a newly built apartment instead of continuing to live in a deteriorating house from the late 1900s, that had last been renovated in the 1930s.
