The problem is not only do all text labels have different sizes in one language, they also have completely different unrelated sizes in other languages.
Standardized icons can be laid out easily regardless of language
the RTL languages are also a pain point, and even German can make your UI designing difficult for length of words. Really, the high variability of width for i18n'ed words in general is I think where the icon-heavy approach originated.
Sort of. 上 means both up and previous, 下 means down and next. Maybe there was miscommunication about contexts when the button meant next and when it meant down in the UI.
No it isn't. That's why hieroglyphics became indecipherable for nearly 2000 years, while all the various alphabetic systems invented during that time--and many of those invented long before--remained readable.
Yes, that's the obvious reason for it, but having a reason doesn't make the icons any more comprehensible. Good luck using those appliances if you're a visitor who doesn't have the manuals and hasn't learned each manufacturer's unique iconography.
That's depends very much on age, class, geographic location. Someone could have grown up imprisoned behind the Iron Curtain, hence learning Russian as a second language. Nonetheless they deserve appliances, websites and infrastructure which they can use and understand.
"What is that? Why don't they put 'menu' there?"
I don't know dad, I'm not the one who made it