And of course, every inspection panel also has structural implications.
Indeed. Cessna, the masters of adequate aircraft thought of this too. The 100/200 series of their aircraft have numerous inspection panels on the underside of the wing. However, it could be required to repair in an area to which inspection panel access is not possible. The wing may have up to five additional inspection panels, as long as it is no more than one per bay. Very forward thinking on Cessna's part.
This sort of maintenance "ease" is not generally considered by civil aircraft buyers, but it certainly saves a lot of repair or maintenance cost later in the life of the aircraft. Sometimes, it's much cheaper to remove the wing from the aircraft to work on it.
The ease with which a Cessna or Piper wing may be removed from the fuselage is also very pleasing. By comparison, single through spar wings (like a Found Bush Hawk or Islander) become really challenging when the aircraft has to be disassembled for transport.