[Quoth]

Originally Posted by NiLuJe

Which means that making the two *distinct* UI-wise is tricky: you'd have to uncouple toggling Wi-Fi power from toggling Wi-Fi connection (which probably entails mostly always leaving the chip powered on, which is... meh',

No. Because quite evidently you CAN use the GUI to turn off WiFi after turning on BT. Most gadgets have WiFi and BT in one chip for a few years. I've Android and Linux. I was doing SW & drivers on Linux and Windows to do with BT, WiFi, 3G, 4G etc from 2006.

I've ONLY EVER seen this issue on FW 4.3x.x of Kobos. It can quite easily be sorted. If it's a design decision, it's unique to Kobo.
It's absolutely not a kernel or chip issue that stops the Kobo Sage, Libre 2 and Elipsa from turning on or off BT or simply showing status and making sure the WiFi state is whatever it was last set to by the user.

It absolutely uses more power to have both on.

I've no objection to people leaving WiFi on, but EVERY maker other than Kobo (that I know) doing any ereader, phone, Laptop or Tablet with WiFi and BT, running Linux, Windows or Android lets the user control WiFi & BT independently.
I've 3 x Android phones, 4 x models Android tablets, Boyue Mars eink, played with Kindle PW4 and set up more models of Laptop than I can count with Linux. All control BT & WiFi separately from the user point of view.

Actually many of the WiFi + BT chips also have FM radio, but Apple disables that because they have no earphone socket; the earphone cable is used as the FM aerial, oddly even on my 10" tablet which is big enough to have an internal FM aerial.

No doubt Kobo has made all kinds of excuses for the bizarre 4.30 & 4.31, at least the 4.32 is usuable as you can look at BT setting without risk and you can turn off the WiFi.
The 4.28.x was certainly unfinished GUI on the Elipsa as there was no real indication if BT was on or off and it wasn't properly done at all.
No doubt in the next FW release KOBO will finally have an indicator on the icon bar beside WiFi and fix the bug, because no matter what they call it, it is a bug.

I'd also like the WiFi & BT icons on the tool bar like * (light) and Aa is when you are reading and tap the page. WiFi on/off used to be accessible there.