Paddles work very well in my RC300h.
Yes I know there are no 'gears' but put the transmission into S mode and the computers simulate gears very well. With instantaneous "PlayStation" like shifts, with the engine revs rising and falling, just like a normal automatic gearbox operated in manual mode. Though far, far better than the manual mode in my AMG.
In Normal mode the paddles change the amount of engine braking.
A gimmick maybe but they do change the way the transmission operates and can IMHO involve the driver far more, especially when 'making progress'.
These e-CVT transmission are streets ahead of traditional, even the most modern, brake-band and clutch auto boxes..