I don’t think a R205/55R16 is one of the major offenders on large wheel on small sidewall tire front. In general, a larger wheel allows for a larger disk brake making for more efficient braking and more stopping power. Mostly the very large wheels are way bigger than the brakes and it is marketing and cool factor and perhaps some handling advantages to the combination. You give up ride quality and durability to get the cool look.
On a Leaf they are looking for the best rolling resistance they can obtain so you get more miles before needing a recharge. The stiffer sidewall means less flexing and less rolling resistance. In the Leaf the tire is selected by performance criteria over the “cool” look.