I'm of a similar opinion. I grew up watching my mother have surgery on both of her wrists for what used to be called carpal-tunnel syndrome and now is just called repetitive strain injury. I've spent probably triple the time by 38 years old that she had in front of a computer, full time developing software, on a standard, non ergo keyboard which is nearly the same (even has clicky button switches!) as the one from her era.
But I've got a mouse too. I use it all the time. It breaks up the repetitive in RSI. I think this is a good thing. We're not all trying to break the record in Mavis Beacon anymore. Most developers agree productivity is not measured in lines of code and yet some seem to still insist that a few seconds at most to move their hands and use the mouse is hurting them somehow.
I don't think you can actually understand the issue if you haven't experienced it; that's just the way our brain works. I was extremely skeptical of Vim-bindings too, for example, and only learned them once I needed a powerful editor that compiles for ARM CPUs. While I don't use Vim anymore (mostly) I'd never want to go back in terms of the modal editing.
Imagine yourself working as a photographer using non-digital cameras. While you know exactly what you want a picture to look like, you can't tell how it actually looks without some major work (i.e. process your film). So, you have to a) take many pictures of the same motive and b) try again later if you're not statisfied.
Of course, you can get very proficent using analog cameras (a trained eye could e.g. certainly tell the proper aperture adjustments for a scene), but you'll have to train that rather inefficently, too. And sure, digital cameras have their drawbacks, but they have a very net positive effect on most photographer's work, that's why you almost find no one using the old methods anymore.
Now, you - as the "analogist" don't recognize all the factors that slow you down in your work. It has been that way for decades, right? It must be the proper way to do things. Now imagine I'm coming along, being used to use digital cameras and forced to use analog ones in your working environment. Can you imagine the frustration I'm going through?
I just want to make a picture of what I need and tell if it worked, if my last two seconds of activity will do. But the old thing has no screen I can use to see if the picture was to bright, to dark or even blurred. That's what the mouse-based workflow feels like after a while: It's unnecessairily slowing you down, constantly standing in your way. No matter if it's not the activity you spend most of your time with - it prevents you from going back to your real work as soon as possible. And if you're used to do the same things without it, you'll very likely get frustrated some time.
Edit: I just realized another good metaphor would be to compare old FORTRAN punch cards (punching them out, giving them to an operator and waiting until the next day for the results) vs. debugging a modern C# application. That'sessentially what you're doing with proper hotkeys: Tightening your feedback loop.
But I've got a mouse too. I use it all the time. It breaks up the repetitive in RSI. I think this is a good thing. We're not all trying to break the record in Mavis Beacon anymore. Most developers agree productivity is not measured in lines of code and yet some seem to still insist that a few seconds at most to move their hands and use the mouse is hurting them somehow.