Pure black background makes it unreadable for me. When I encountered this on websites, i use the Firefox function to turn it into a black on white background theme, so my eyes don't hurt reading longer text. Same logic applies to the terminal, especially when programming. I think pure black as a background shouldn't be default. However I do actually appreciate darker tones as background, but its never pure black. It depends on the combination of colors for text (and on the rest of the system theme).