I think it's testing how fast you can go from ~25 (depends on how quickly you dare take a roundabout) to 70 in between each roundabout that is the best part of living next to MK.
I visited family in Swindon, so they decide "we must see their Nested Fractal Roundabout of Doom" because that's obviously their primary tourist attraction now.
I'd probably guess you were fascinated by the idea of roundabouts.