Several manufacturers had high dpi screens about 300dpi in phones before Apple. None that I'm aware of matched Apples exact dpi but then again, they had no need to exactly quadrupel the pixel count in the original iPhone while still being roughly the same size.

As far as the aluminium goes Apple has fetishised their materials choices for a long time and had as many hits as misses e.g. "Titanium" paint that flakes off, White iBooks that discolored, white iPhone 4s that they can't manufacture. Others generally don't bother as their customers don't want or need it. I'm not sure Apple users do before they are trained to by Apple.