Raked wings is another possibility to solve the "problem" with the induced drag.
AFAIK are raked wings the better solution for long range aircraft -> the pressure difference between bottom and top wing in cruise is low compared to the landing configuration (with higher angle of attack and flaps set), so winglets working for start and landing but also producing some drag in cruise. Raked wings are less effective during start/landing but better for cruise flight.
But why are A380 and A340-5/600 equipped with common winglets oder wingtip fences -> i don't know, but i'm sure a lot of construction engineers at AI will know it.
All in all the performance for the whole flight counts.
mike