The Part 107 exam is directly taken from the Private Pilot written exam. The FAA simply repackaged some of the material and questions. Everyone has different opinions but I believe there are many parts that do not apply to UAS pilots. Examples include crew resource management, weight and balance, the effect of bank angle on stall speed. While those are all very important when flying a fixed wing aircraft, they have little to no relevance in flying a quad-copter. I specifically said quad-copter because stall speed obviously does have some relevance in flying RC fixed wing aircraft.
Since they had the opportunity to write a relevant and targeted exam, they really could have (and should have) done a much better job. I fully agree that if you want to fly commercially in the NAS then you should definitely know how to read VFR sectional charts and know what the airspace is above your head. That seems to be the tough part for most new UAS pilots who say it is too difficult.
On the other hand the METAR standard is probably something that the average UAS pilot has no need to know. With today's technology, Internet connectivity, portable devices, and weather apps, it just isn't something that we use.
They did tweak the content when they created the slightly shorter recurrent test, but I haven't looked to see whether the initial test has changed.