What's the justification for doing maintenance sooner than VW recommends? (Not being snarky, actually curious - I'm at about 6k miles so the 10k is still theoretically a ways off.)
None. The recommended intervals are not set to the last possible mile/day to do the maintenance or the car will die the day after. There's a pad built in to the schedule because it has to be conservative enough to let the car live. Unless you are really hard on the car and driving in such a was as to cause fluids to break down early (tracking every weekend, slamming on the brakes every single stop, etc.), driving normally and changing fluids at the manufacturer's recommended intervals is completely fine. Changing fluids early does nothing but cost you money.
If you drive normally, the one fluid that could always stand being changed early is brake fluid as that absorbs moisture even if you don't drive at all and can affect your braking performance when too much water is absorbed.
Yes, fresh, clean, new fluids are good. But changing them early won't buy you another 200,000 miles.