I feel somewhat the same about pencils, when it comes to holding and using one. A #2 is like sketching out thoughts, no matter what you're doing. All preliminary. I'm freer, more open to trying new ideas because if they don't work out, they can be erased. And I prefer the look of a pencil sketch to one done in simple pin and ink (the more elaborate styles using India Ink are the exception; those go both with pen and brush).
None of this is something you can do with a ballpoint pen or anything felt tip, not really. You can approximate the feeling...and I have, sometimes...but those are really more work-a-day stylos good for business and finance, not as a partner in your thought processes, and their aura is commercial and plain.
Problem is, you can't use fountain pens except on good paper; otherwise the ink seeps through and you wind up only able to use one side of the sheet. I avoid writing with one in my journal, for example, because I do that in a composition book. Same for legal pads; one side only. And on checks, you have to wait till the ink dries before you can do anything more with it. I don't remember it always being like this.
When we lived in England, our neighbor had a teenage daughter who would babysit for my folks. And she'd do her math homework with a fountain pen on paper that held it fast. I could watch her for hours. I tried it a few times and quickly returned to the safety of a pencil, because I made a massive mess of the page. But it took a lot of ink for it to seep through to the other side of the sheet.
I have Calligraphy pens, and pens I've used for India ink sketches, but the feel of a reservoir pen nestled between your finger is just...nice.