I'm against bringing back refuelling - I can think of several bad reasons and no good ones - but I don't think the ban explains solely or even mainly the increase in overtaking that we've seen from 2010.
Overtaking now may be considered less 'significant' because of KERS, DRS and Pirelli creating bigger performance disparities. But, without DRS, Pirelli tyres and KERS, would cars actually be able to overtake at all? Under Bridgestone the performance profile from Saturday usually carried through to Sunday; the cars moved away in grid order and unless someone had stalled, overtaking was a redundant concept. I don't think the refuelling ban on its own has solved that problem (if you line cars up fastest to slowest, they won't pass each other) but only in conjunction with these other variables, that mean different cars are fast at different times in the race, or in a particular lap.
Perhaps there's a better way of doing it, but surely it still needs to be done? With the level of investment and technology in the sport now, and greater understanding of, and control over, the variables influencing speed, giving teams a free hand probably means the performance equation will be solved with a high degree of consistency, and unpredictability takes a back seat.