> It also forces the planners to do a good job when designing junctions.
Living in Dublin, I have the opposite perspective on this.
I much prefer roads with painted lanes (or better, no cycle lanes), as having cyclists on the road necessarily makes motorists more aware of their existence (particularly when you have a lot of cyclists, so this effect increases with usage). I agree that painted lanes give more of a false sense of security to cyclists than anything (motorists will still ignore you if they can), but with segregated lanes they always ignore you.
This seems fine until you realise that well-planned segregated lanes are much more difficult to achieve (and where I live, an absolutel rarity—we have some of the most dangerously haphazard segregated lanes), and even very well-planned segregated lanes are still quite limiting in terms of cyclist movement. They lead to cycle congestion, cyclists become more of a danger to eachother, and you will always have entry/exit points which are far far more dangerous than if the cyclists had been on the road and visible all along.
On a more political level, they also reinforce the idea that roads belong to cars, and that cyclists, by using them, are invading them and should not be there.