I sometimes wish my 5MT Insight had an extra gear. Not a taller top gear, as anything taller would be mostly unusable in any place that has wind or is not completely flat, and it's already only at 1700RPM at my preferred cruising speed, but 1st, 2nd, and 3rd are very far apart and often force me into suboptimal gears when driving around town.
2250RPM in 1st -> 1150RPM in 2nd (13.5mph)
2250RPM in 2nd -> 1400RPM in 3rd (26.75mph)
2250RPM in 3rd -> 1750RPM in 4th (42.75mph)
2250RPM in 4th -> 1850RPM in 5th (55.5mph)
Luckily, most of my driving is rural and once I'm actually rolling, I'm very rarely below 3rd gear.
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I can see both sides to this.
More gears = more parasitic loss in an auto, more weight, and a 9 speed would be a nightmare in a MT.
On the other hand, more gears = more options to stay at the perfect RPM/load combo.
I'm inclined to believe that, with how wide the efficiency band is on modern engines, any more than 6-7 gears is getting deeply into diminishing returns, but I can definitely see how a 6 or even 7 speed could be beneficial over 5.