srsly though, the point as I see it is this: is the roundabout there to regulate traffic efficiently, or is the roundabout there to force you to slow down? By deliberately placing obstructions in people's line of sight, the roads authority is very likely hoping that people will slow in order to check they aren't going to mash their kiddie-filled SUV in to a bus. I feel that the argument of everyone (it seems) is that people scan the roundabout for danger well in advance of the place they're now forced to do so. Because the choice of place to scan the roundabout is now forced apon them, a) people regard it as annoying and b) people have to slow/stop because they don't know for a fact the roundabout is free, thereby inconveniencing themselves and other road users.
Very recently I saw the NL equivalence of a tricked out Nova cut across two lines of traffic and take a blind corner at speed on the wrong side of the road. Sadly my fervent wish that a bulldozer would magically appear at the corner to blindside the scumbags and remove them from the gene-pool did not come true that time. The point of this anecdote is that in the light of the roundabout story above the people whom the design is engineered to combat will not regard it as a trigger to slow down and take due care, but perhaps more a challenge to blast through as fast as they can.
Roundabouts are put in place to prevent serious/ deadly/ high-speed accidendts . I think, thats the prime modern argument.