What do you think that Rack "tries to mimic [ from hardware ]" that Bitwig's grid does not? Are you just refering to the knobs etc.? If so, that's not in Rack's domain at all: module developers control their module's appearance, and there some which are extremely skeuomorphic, and some which are not. Bitwig's Grid is uniform and consistently non-skeuomorphic, but is also (IIUC) not open to 3rd party device/module development.