Dismounting/mounting the back wheel on a "Eurobike"
On a bike with a full chain case, any operation that requires removing the rear wheel is a bit of a pain. That would include replacing a spoke or a tire.

Repairing a roadside puncture, on the other hand, can usually be done without removing the wheel; and that is indeed the traditional method in countries where this sort of bike is common. Henry Cutler of Workcycles describes the procedure as follows (source):


  
  Set the bike on its handy parking stand.
  Try to find the source of puncture and set it in an accessible spot.
  Open the tire from the left (non-drivetrain) side.
  Pump a little air into the inner tube to locate the puncture(s).
  Remove (all of) the offending objects and remaining air.
  Patch the inner tube.
  Refit left tire bead onto rim, making sure valve sits straight.
  Pump tire up and continue cycling.
  


The traditional Woods valve (aka. Dunlop, English, Dutch, blitz) adds an extra dimension to this, as you can effectively replace the valve as well without removing the tube from the wheel. In Norway where I live, a replacement valve is often included in patch kits to this day, even though most new bikes come with Schrader or Presta valves.

This all makes sense, I think, as practices developed at a time when rubber was rather expensive. Make your tube last as long as possible by patching holes and replacing valves as needed. With such practices established, the advantages of a full chain case may outweigh the added complications in the remaining cases where you do have to remove the rear wheel.