No matter what Eli Schiff argues, it’s just a style. A reaction to what came before – the green felt abomination of Game Center, the rich Corinthian leather of Calendar, or random cartoon characters in the interface.
Flat design isn’t why designers are encourage to code, it’s not why prototyping is important, and it’s not why design careers have the lifespan of a mayfly.
Arguments in bad faith don’t help.
I do agree with Mr Schiff that it’s highly overblown as a design trend, and needs to be de-coupled from our perception of modern design. Everything else? Where the fuck was he when Flash was cool? I have one name: 2advanced. If you know what I’m talking about, you’re cringing inside.