From what I can see, there are very few people who can use a manual gearbox properly anyway, I really don't know why they bother with one, and don't just give up and go for an auto from day one.
Frankly it takes quite a lot of skill to use a manual properly, which is why we enthusiasts enjoy it, and most people simply do not have the inclination to completely master the intricacies of one. How many people actually 'heel n toe', block change, rev match or are even in the right gear at the right time for the speed and road conditions they face? Many people just judder along at too low revs, drag the clutch on downchanges, often start in 2nd, and are just cruel and harsh with the clutch work.
The foregoing obviously doesn't apply to anyone who drives a Morgan, of course!