Speaking from 4,396 hours of air time,
I simply wouldn't operate, or even get on an airplane that presented a "slight gap" at the wing attachment points! Pix is correct; generally there is a PVC or Aluminum fillet that covers any open seams in an airplanes skin, especially at the wing root. Aerodynamics is a strange and unforgiving creature which lives by the old adage: "One problem will invariably lead to another". The story of "Columbia" demonstrated that concept tragically well.
It may be the only results of leaving a slight gap, would be an irritating "whistling" sound, but think about it, that "whistling" translates into wind interference, which translates into DRAG. In a high speed aircraft, this Whistling can very well translate into disaster, by giving birth to another dreaded creature known as "Harmonics", which can literally dis******emble an aircraft in flight, if the source is not discovered and corrected.
Of course, the one factor that links all this together, is SPEED, but even a Cessna 150 uses PVC fillets around the landing gear and wing strut attachment points to prevent unnecessary drag. If there isn't a fillet, the seams are tight, so they'll be no air resistance.
You know how sensitive your ears are to a "different sound" while driving your car down the road? Pilots are no different, and are keenly attune to any Different SOUND or FEEL that manifest itself during flight. In a Chinook Helicopter, with the high decibel forward transmission whine and other ******ociated noises experienced by the pilots during flight, if the FE dropped a wrench on the floor back in the cabin, I guarantee you he would instantly see two heads looking back through the cockpit tunnel to see what had just happened! Not to mention taking a hit, which opens up a whole new can of worms known as Battle Damage.
Frank
**It appears the Forum Filters are censoring the letters "A S S" in my post????**