In Spain it's not only 60s/70s, pretty much everything build between the 60s and the 90s is not only ugly AF, but very low quality. And Barcelona is not even the worst offender. In northern spanish cities there's a lot of grey in the buildings, with basically no insulation in a humid and cold climate. My GF used to joke it was colder inside her home than outside.

After the new construction code in the early 00s the quality has improved a lot but we still build very ugly buildings.

No wonder why people chose to gather and spend their time where the historial centers are.

Seems architects really refuse to extract some lessons from this.