I'm a "old" soldier not a sailor but why was a ship commissioned in '61 retired thats hardly old in ship terms.
It's not surprising at all. CVN-65 is the second oldest serving ship in the US Navy. CV-6 was only in commission for 9 years( thanks to the jet age making her too small and structure too weak for jet fighters). 50 years is pretty long for a ship to be in commission. Especially when Enterprise is her own class making maintenance and up keep expensive( especially when the ship was expensive to build in the first place hence why only one was built in a class planned for 6).
She was planned to serve until about 2015( when her next refueling would be due) to shorten the time until CVN-78 was finished to replace her, but they retired her early to keep costs down.
The Enterprise was one of the Navy's first ships . It was also the first nuclear powered carrier. Thus the tradition.
Actually CVN-65 was named as a part of the deal the US Navy made after the screw up of not being able to make CV-6 a floating museum and the scrapping of her.