The case is pretty simple:
The club had to modernize the Camp Nou and introduce VIP rings in a way that was affordable. They couldn't rebuilt the entire stadium, as it would have cost around 2-3 billion and forced the team to play 3 years at the Montjuic at the very least. But thanks to the unique structure of the Camp Nou, where the third stand was later added to the original 1957 stadium, they could demolish and rebuilt it to get exactly what they were looking for:
- VIP rings
- A symmetrical third stand to have a roof
- A new design from outside
- much bigger space for parking, stores and other activities
The interior stands couldn't have been designed differently, since they can't overhang the VIP rings and they also had to built them one above the other, as they couldn't put one ring between the first and the second stand. So yeah, with all that in mind, that's the only possible and affordable interior design. And the look will be completely different and menacing for all away teams, once the roof is up.