The stop/start facility should be stopped and started as little as possible to produce longevity for consumable parts. The starter, oil, oil pump, battery, engine components are all effected by the stop start process so the fewer amount of times this process activates the better for you engine. VW did not fit this device for the longevity of you engine, my guess is it was fitted purely for the emissions/MPG process. You do not want the oil pump and oil flow stopped and started constantly in any engine...
The starter motor on stop-start enabled cars is beefed up, the battery is optimised for stop-start in the way it is charged and discharged, and on the R at least, the car is using an electric coolant over-run pump (V51) to stop the turbo bearings from overheating for a short while after the engine is turned off (there's a few R2D2 sounding noises and the low hum) - I'm quite sure the GTI engine (and all variants of the current 2.0TSI) has this but can't confirm it.
Stop-start won't kick in until the engine is sufficiently warm - VW have clearly considered the effects stop-start would have on a stone-cold engine, battery and starter motor (when the oil has thinned with warmth to not make restart effort as hard as the first start). By far the most engine wear occurs on the first cold start-up when the oil is not on the internal components of the engine after being sat for hours/overnight. If stop-start put a huge amount of wear on the engine and ancillaries, i'd expect to see a noticeable amount of metal in the oil filter at every oil change.
Stop start won't make VAG engines last half the miles they used to, considerations have been made in the design and utilisation of stop-start tech. I'm sure most of the other Marques did the same when they introduced stop-start.
Things have moved on in engine tech and lubrication tech since the 80s...
