I MUCH prefer the original thumblatch, but they are hard to come across and they are not very strong since they are "metallized plastic".
Reportedly the switch was made because in crashes, the tank would pop open, spilling fuel everywhere and causing a fire hazard. Also, there was a fellow, in the UK I believe, that got into a crash and he slid forward onto the tank and the opened cap damaged his er...gear, and he had to have one or both nuts removed.
The resulting lawsuit helped push the switch to the "locking" gas cap and later, the flat, low-profile gas cap flap.
