I like the modularity, but I'd feel better if it came with the "blanks" that just extends the inside USB-C port towards the outside.
I feel like things would not look like nickel-and-diming if those blanks came with the laptop, and they just priced them in the final price. Or even better, offered the option to "upgrade" one or several of those to whatever you need.
Of course you can use the modules on any other brand of laptop. It's not going to look pretty doing it, but I've routinely used the USB-C to USB-A, as well as the mini SSD, on a MacBook Pro.
Colleagues borrow them all the time when they need a SD card or MicroSD card reader. Is it as pretty as a dedicated reader for those cards? No, but it does the job.
Saying they're proprietary is misleading a bit. The form factor makes it awkward to use elsewhere but they work just fine anywhere you plug them into.
I feel like things would not look like nickel-and-diming if those blanks came with the laptop, and they just priced them in the final price. Or even better, offered the option to "upgrade" one or several of those to whatever you need.