It probably is an acquired taste. I think I took to it so easily because I never really drank original Coke/Pepsi to start with. I may have had the odd one or two, but, being Scottish, the soft drink I had a fondness for, growing up, was always Irn Bru.
So I probably went straight on to drinking the diet versions of Coke/Pepsi when they came out without ever having first build up a taste for the originals. Guess that helped.
Although, OTOH, these days I also drink the diet version of Irn Bru and the original is too sweet for me, so the theory kind of falls apart there because I don't recall having much of a taste transition from the sweet original to the diet version.
Talking of awful tastes though - I'm old enough to have been around when there were no diet versions and I do recall one of the first diet Coke's to come out was something called Tab. Now, that was positively foul. As I recall, it didn't last long and then shortly thereafter they invented new sweeteners which were a lot more pleasant.
LabRat