Gravity might not be a force, but it is described by a field theory. And field theories can/must be quantized. So the question is really just a different way of

Gravity might not be a force, but it is described by a field theory. And field theories can/must be quantized. So the question is really just a different way of asking, if we need to quantize gravity: https://physics.stackexchange.com/questions/6980/what-are-the-reasons-to-expect-that-gravity-should-be-quantized https://physics.stackexchange.com/questions/6980/what-are-th...