I'm well aware of what the European test requires, since I have a European license.
It teaches the bare basics to be on the road and not die on a normal sized bike. It is the starting point from which to learn how to handle a bike properly.
If someone has just taken their test they are not ready to handle a 650 to it's full potential, never mind a tall 750 like the new TransAlp. Getting a smaller bike and finding out how to scrape the pegs at 30kph in Moto Gymkhana is a good start for the road, for adventure riding trials is the best.
Only good for masochists, it'll need a new one of everything from rusted-in brake seals to rusted-in swingarm bearings. And when it's all done you'll be left with a bike that's only slightly better than other featherweights, is completely impractical, and cost the same as a new bike to put together even if it was free.
If you already have another one that runs nicely but needs new plastics, then go for it!