'Exchange of virtual photons' is a metaphorical expression used to describe artifacts of perturbation theory, it is not necessarily a real process. There is no widely accepted model of what really happens on microscopic scales, we only have equations and those are often replaced by simpler perturbation scheme. So, explanations of attractive force are welcome, Le Sage - type models including.
>There is no widely accepted model of what really happens on microscopic scales,
There's no experimental reason to come up with one - virtual photons work, which means anything else is at this point a matter of philosophy. That's not to cast off philosophy, of course.
Virtual photons work in a very limited way (metaphorical language describing perturbation theory). Physics outside of applicability of perturbation QED (bound systems of charged particles, gravity) is not a matter of philosophy.
