I think Stockholm's greatest problem is the geography. Everything going north or south in the entire region has to pass through the same few islands in central Stockholm, all options are awful. Therefore we end up with the horrific traffic on for example Hornsgatan or Sveavägen used for essentially thoroughfare when they instead should be calmed nice livable streets.

The way to solve it is by finishing the bypass (Förbifart) Stockholm and an eastern ring connection and then start greatly limiting traffic going through the center.

Completely agree outside the inner city. You can feel that it was designed in the 60s and 70s and then never touched again.