Standardization of machines and gadgets has certainly not been around for "hundreds of years", Jorgen. The industrial age only barely began in the 1700s, didn't really get rolling until the 1800s, and there were few 'standards' in the modern sense until the middle of the 1900s. For example, computers in the modern idiom didn't even exist until the 1980s and later. Cameras didn't exist at all until 1839 and didn't approach a modern notion of standardized operation even on 35mm film cartridges until well into the 1950s.
Even today, in automobiles the location of reverse gear on a manual transmission car isn't in a standard position.... Same for headlight switches, etc. And the automatic transmission PRNDLL pattern standard dates to the early 1970s before it became a standard. (And seems to be going away now that there are hybrid-auto-manual paddle shifters, etc...
No camera I know allows you to customize the power on/power off button, nor does any smartphone to the best of my knowledge, so that's a bit of hyperbole. You customize how your smartphone's camera works by installing apps that control the camera differently, and learn how the apps work ... I have several of those and use them when their specific features fit my needs or desires. I use the standard Camera app most of the time, because most of the time it does well enough and I don't have to think about it.
I don't recall that so many cameras all operated the same, according to some standard, in the '60s, '70s, '80s, or '90s either. Those cameras were a lot simpler then, however, and it was just easier to figure them out because they didn't do a heck of a lot other than move film, set exposure, and release the shutter. It took some time to figure out how to load a Rolleiflex Automat, which was different from loading a Rolleiflex T, which was different again from loading a Yashica twin lens reflex that looked almost identical. Never mind loading and using a Hasselblad vs a Mamiya RB67, or a Leica M3 vs a Leica IIIf. I jammed a friend's Nikkormat FTn three times by changing lenses the wrong way, despite that I'd done it before AND had a Nikon F Photomic FTn myself. All different...
I think you're just confusing yourself by thinking that you MUST customize everything because you CAN. Stop. Return the E-M1 to its defaults and learn it well just like that ... It works well enough for the 85th percentile use. Then tweak a couple of small things as they make sense to you and fall properly to your fingers, so that it suits you to the 98th percentile, and then accommodate the 2% that doesn't.
Simplicity is a state of mind more than anything else.