Why ship a low power charger with an overkill thick cable?
1.7A isn't exactly low power.  As you note, the several-hundred-watt desk lamps run on 230V, so their current requirements are much less - They could actually be lower ampacity than your charger!  For example, this is almost 4x the power levels of USB.

As you probably know, it's the current that determines the size of a cable, not the power. I calculate that your cable could carry up to about 8 amps, which is a little more than 4x the rated capacity of your charger, which may put out higher amperage under short-circuit conditions.  In a short circuit condition, you'll want a fuse or PTC in the charger to cut out, rather than burning the cable.  

It's not really overkill.