> Compared to modern UI/UX which just slaps me with how stupid it thinks I am
Because most average users of any software absolutely fall in that bucket. My mom can use the Facebook app on her phone just fine, but I wouldn't even dare to suggest that she try to convert an eBook on Calibre and transfer it to her Kindle.
I earnestly think it's motivation and there's this societal pressure that software "is too hard." Just like your mom can use the Facebook app just fine. I have trouble using it, I'm worried anything I type into a box will turn into a public post with notifications going into everyone's inbox, and I've also mostly avoided it for over a decade. My grandmother over a decade ago figured out how to buy a webcam, install it, and use the software when grand kids were born.
Or Blender, or the GIMP, or FLStudio, or AutoCAD, or Visual Studio, or Lightroom (Classic), or Filezilla, or Photoshop, or or or or...
And while you might think that the above obviates my argument, when was the last time something new came out? All the best software we have nowadays is old, designed before current standards
Both things can be true - a person can prefer a more complicated and feature rich UX, while most people prefer a simpler UX that doesn't provide as much control.
You can definitely have a simple to use UI that still has all the same complex functionalities of an esoteric one. The more advanced features will just be more hidden away. To me, the only real advantage to an esoteric UI like calibre is the ability to do things faster and easier once you have learned it.
Because most average users of any software absolutely fall in that bucket. My mom can use the Facebook app on her phone just fine, but I wouldn't even dare to suggest that she try to convert an eBook on Calibre and transfer it to her Kindle.