Why should one upgrade Fedora whenever a new version is released?

[Michael Hennebry]

On Sun, 14 Jul 2013, lee wrote:

> Reindl Harald <h.reindl at thelounge.net> writes:
>
>> Am 14.07.2013 01:25, schrieb lee:
>>> From what I've been reading, CentOS isn't upgradeable at all.  If that's
>>> true, I'm surprised you're using it.
>>
>> * you use it if you do not need new features over the lifecycle
>
> For which use cases can you predict that you will be fine with the same
> software for the next ten years?

Something about which I am ignorant:
Which changes require new releases and which do not.
Would someone be kind enough to give me
examples of each between F14 and F19?
Why were new releases required?

-- 
Michael   hennebry at web.cs.ndsu.NoDak.edu
"On Monday, I'm gonna have to tell my kindergarten class,
whom I teach not to run with scissors,
that my fiance ran me through with a broadsword."  --  Lily