As a way for even lazyer people to use a joystick as a shifter for people with wheels with no stick, surely it would be an idea to be able to assign an axis as shift up/down.
And, anyway, H-Gate shifters are beyond the means of many LFS drivers - and they might just be cheap and have a joystick. Besides, if you drive mainly the FOX and GTRs, those cars are sequential in real life.