Not just the sound, but the expressiveness. Electric kits do not create noise directly from the performance of the drummer. There is a layer of interpretation and mapping to sound. So they can only reproduce sounds pre-programmed into them according to variation that their senors are designed to respond to. Acoustic kits are making noise because of the physical properties of the kit itself. So you will always be able to find sounds on an acoustic kit you cannot reproduce on an electric kit. And the range of expression present on an acoustic kit will always be infinitely greater than an electric kit.

Full disclosure: I own an electric kit.