I love side projects. I have LOTS of them, in various states of completion, using a wide variety of technology stacks and programming languages. You can check most of them out on my GitHub page here: https://github.com/WriterZephos.
I would guess that about half of my side projects are probably websites or web applications, including an old personal blog site or two. I think one of them was even built in PhP (I did that one in college, before I knew better).
So why did I choose WordPress for this one, instead of doing yet another side project? Well, I usually start side projects for one of three reasons: I think it could make some money, I am passionate about what I am building, or I want to learn something.
This time, however, just getting a blog up as soon as possible outweighed all of the reasons I would want to build it myself. That said, I probably will build a blog site from the ground up in the near future and transfer this domain name and all the contents here over to it. But for now, WordPress will do just fine.