I’ll point out the obvious that this is entirely based on perspective. An individual whose dominant mode of transportation is not driving would probably disagree.

You know what makes bike lanes more appealing and safer (amongst other things)? Not being next to speeding cars.

Why do you need to go faster in a city center?

You probably don't need to go faster in the city center, but you need to get to the city center somehow.

The limit is active in city centre and residential areas only.

You don't need more speed, you need better planning.

Agreed. That's what I put in my original post.

Edinburgh doesn't enforce its 20mph zones, I follow them anyway. And I don't believe I actually make progress through the city any less quickly than drivers who speed, because it's rare that I'm not in any case sitting behind the speeders at the next red light.

Arterial roads are normally still 30mph, and it's not a huge city so it doesn't take that long to get from the outskirts to the centre. Or when it does, it's not because of low speed limits.