There are many reasons why I enjoy the hobby of fountain pens in particular and pens in general. They range from aesthetic, to mnemonic, to a feeling of connection to history. For me, there are even philosophical reasons to enjoy facets of the hobby. I'll try to break them down and elaborate.
The parts of a fountain pen can be beautiful in their simplicity and in their appearance. Some of the finer pens have an exquisite beauty that comes from rare lacquers, like the Urushi process[1]; rare and dangerous tree sap turned into careful patterns. These materials change over time with use, becoming ever more personal as you use and care for them. Beautifully crafted nibs that hold patterns and designs expressing logos, orbits, flowers, coats of arms, all in a tiny space are wonderful to me. The pens themselves can be little works of art.
Underlying all of that, even in the less expensive pens, you have very basic principles of physics and fluid dynamics coming together to support one of the most basic human freedoms: self-expression in words and pictures. In some senses, this form of self-expression, when well-used, can be an elevating facet of one's daily life. I find the possibilities here beautiful, and feel a connection to that potential when using pens.
There is craftsmanship to appreciate in a well-made fountain pen. Like a well-made tool, or a well-made ship, sword, table... you name it... Using something so well-suited to the task of writing is a pleasure all on its own. Even the ritual involved in caring for a fine implement is a pleasure. Disassembling the pen into its component parts and cleaning it out holds the promise of refilling and more writing; the exploration that will come with new inks and new thoughts. This also gives me satisfaction.
Then there is the tinkering aspect. Many pens can be adjusted to the suit the wants and needs of their wielder. Swapping out nibs to gain different effects during formation of the letters, tuning nibs to your preferences, playing with different filling mechanisms... All of these also bring enjoyment.
Aesthetics, craftsmanship, and tinkering aside, there is the act of writing with these fine devices. I derive satisfaction from having filled a notebook page with text, even if it is just meeting notes. When it is actual expression, organized thought or expressed feeling, so much the better. Every stroke upon the page, every word chosen, every scribble in confusion was something I did. It was a small part of me, existing in this stream of reality, made evident on paper. No one else could have produced exactly what I did on the page, for better or worse. I'm not saying it has any intrinsic value to anyone but me, but I find it a very satisfying activity.
There have been a number of studies linking the activity of handwriting, painting, and drawing to good effects on executive function, and, in the case of journaling, to emotional well-being. I won't claim this is why I do it, but I can give anecdotal evidence that I've noticed improvements in memory and my ability to manage anxiety. I realize this is the "citation needed" portion of the comment. I'll have to search for those later [2].
Even if these weren't factors, I choose to write; for pleasure, for work (notes on paper are far quieter than rude tapping on a keyboard during meetings), and sometimes to occupy my hands. That said, I want a means that is an improvement over disposable plastic pens that get tossed in landfills. If I seek pens that are not disposable, it leads me to fountain pens and fountain pen ink. A 4.5 oz. bottle of Noodler's Ink, and the free fountain pen that comes with it, are more worthwhile than dozens of disposable pens.
Even with the more expensive pens, you will get use from them for decades, perhaps even more than one lifetime. I will admit, however, that practicality is the least of my reasons for digging in to the pen hobby.
Personally, I also get a sense of connection to history. This is so even when using the modern refinements brought to these instruments. When I use pen and ink, I join a long tradition of people who left their mark upon the page. From scribes copying manuscripts and writing digests in the catalogs at Alexandria, to the letters penned and exchanged between famous scientists, authors, composers, and politicians; I get to feel a sense of joining them. Not in significance, or in the impact of my words, but I can imagine some tenuous connection to those people. They, like me, took pen in hand and wrote. In some minute sense, I am like them.
For the pen's connection to freedom of expression, I will also forever love the hobby.
I haven't even mentioned inks in all of this, as that would extend this post far longer than I have time for.
What has any of this to do with hacking? Writing is an act of creation, just like woodworking (the original hacking), or coding. Just as we discuss mechanical keyboards, programmer's editors, and programming languages for software construction, pen, their construction, alteration, care, and the inks used with them, are similar.
These are some of the reasons I like pens. Your mileage may vary. And yes, I wrote this out with a fountain pen first.
[1] https://jpninfo.com/56468
[2] https://www.forbes.com/sites/nancyolson/2016/05/15/three-way...