20k servicing is for high mileage.... its the long life service interval and its the standard one set on all Mk7 golfs. Its 20k or every 12 months, whichever comes soonest (mine actually is currently b!tching about a service in 20 days despite me having done about 2k since last service!)
And the oil used for long life is the same one as is used for the low mileage annual interval.
If you are someone using a car for 20k miles a year (which I am), you aren't keeping it forever (unless you are nuts) and during its limited life with you its not going to cause any issues and even if it does, VW warranty will cover it.
On average, UK cars have a 10 year life...and will be built with this in mind.
You just have to think about it like that.