

I think it heavily depends on the files one has to browes the most. I deal with text files all the time, so i dont need an icon to jump in my face telling me, that its a text file.
The media-, design people I know love the previews that icons give them, because its much easier to spot the image file, they are looking for while scanning through a directory

Come on, They build this stuff open source, so that you can self host it completely free of charge.
Advertising their own paid infrastructure to counterfinance development is a no brainer