Writing for the latest python version is just simply... fun. Even the name 'python 3000' or py3k is amusing.
It's been a joy over the last week plugging away at a few personal website and game projects using the latest python version. Over the last year I've been involved in upgrading existing code to the latest versions of python... but not really in writing it JUST for the latest versions.
No need to consider backwards compatibility problems... older pythons be damned when programming for fun! I'm able to take advantage of the latest python features in deep architectural ways. To fiddle around with the new deep magic python internals. But the new deep magic parts aren't the best bits though... it's all the elegant little improvements that make a difference.
It is of great delight finding python 3 compatible modules. It turns out that the modules available for python 3 are often of quite good quality - and well maintained. There's not all that many of them around, so it can be good just to browse through those python 3 packages that are available.
All of this fun makes me reminisce to the days of playing around with python ten years ago. Perhaps I'm romanticising it a little bit(well I definitely am!). However when first getting into python all those years ago was quite a thing. It was probably the small community, and the idea that optimizing for the programmer was more important than optimizing for the computer(no more squiggly braces :). Like the halcyon days of python2, there is a smaller community of python 3 programmers, and there are a bunch of new techniques and tricks available from python 3. These two factors remind me about what it was like to get into python all those years ago.
Most of the programmers doing python 3 stuff are either doing it for fun, or doing it for the good of the python ecosystem over all, that is to make python better for people rather than better for the machine.
So if you need a reason to get into python 3 it is this: python 3 makes python fun again.